Last Updated Mar 24, 2016 10:37 PM EDT
BRUSSELS -- Six people have been detained in raids around Brussels linked to this week's attacks on the city's airport and subway system, Belgian prosecutors said.
In a statement late Thursday, federal prosecutors said that the arrests were made during raids in central Brussels, Jette and the Schaerbeek neighborhood.
"It will be decided tomorrow if an arrest warrant (charges) are brought against these people," spokesman Eric Van der Sypt told AFP.
Earlier this week, police found a large stash of explosives and other bomb-making material in an apartment in Schaerbeek believed used by the suicide bombers.
Schaerbeek residents described hearing detonations during the police raids. It was unclear whether they were explosions or controlled detonations.
Also Thursday, a man who had been in the "advanced stages" of a plot to launch a terror attack in France was arrested in a Paris suburb, CBS News correspondent Elaine Cobb reported.
French interior minister Bernard Cazeneuve said there were no links "at this stage" between the plot and the attacks against Brussels this week or Paris in November.
Authorities lowered Belgium's terror-threat level by one notch Thursday, although they said the situation remained grave and another attack is "likely and possible."
Belgium had been on its highest alert ever since Tuesday's bombings in the Brussels airport and subway that killed 31 people and wounded 270.
Survivors of the airport blasts told harrowing stories of survival. From his hospital bed, Sebastien Bellin told CBS News he knew how close he came to death.
"You're about to die and you're just like no, no, no, no," Bellin described. "And I can remember just fixating on a point in the ceiling and just being like 'OK, no, they're not gonna get me. They're not gonna get me.'"
Bellin told CBS News correspondent Vladimir Duthiers he was walking to airport security when the first bomb went off. The power of the blast sent the six-foot-ten athlete flying more than fifty feet through the air.
"I remember falling down, and my hip just exploding. I looked down and you know I see like massive bones just sticking out and then I hear the second explosion," he said.
"I think that's really what saved me because I was already on the ground when the second one went off."
Helpless and bleeding out, a stranger dragged him to safety.
"He's the one that put kind of a cloth to stop the bleeding on my leg because my leg was completely detached and I was screaming. Once I made it to the ambulance, I knew I was going to be OK. So that was the first relief, like OK, you made it."
Bellin is recovering from surgery and is looking forward to being reunited with his American wife and two young daughters again.
Despite increasing evidence of intelligence and law enforcement failures to prevent the suicide bombings, Belgium's prime minister refused to accept the resignations of his justice and interior ministers Thursday.
"We don't have to be proud about what happened," Justice Minister Koen Geens said of the government's failures to halt the attacks. "We perhaps did things we should not have done."
Less than a mile from the bombed subway station, European justice and home ministers held an emergency meeting where they condemned the "terrorist acts" as "an attack on our open, democratic society." They also urged the European parliament to adopt an agreement allowing authorities to exchange airport passenger data.
A manhunt continued for one of the Brussels airport attackers who was recorded on a surveillance video and had fled the scene.
Prosecutors declined to comment on reports from Belgian state broadcaster RTBF and France's Le Monde and BFM television that a fifth attacker may also be at large: A man seen on surveillance cameras in the Brussels metro carrying a large bag alongside one of the suicide bombers. It is not clear whether that man was killed in the attack or is a fugitive.
Authorities drew a line between the Brussels bombings and the Nov. 13 attacks that left 130 dead in Paris. Both appeared to have been carried out by the same Belgium-based Islamic State of Iraq and Syria (ISIS) cell.
Prosecutors have said at least four people were involved in the Brussels bloodshed, including brothers Ibrahim and Khalid El Bakraoui, identified as suicide bombers. European security officials identified another suicide bomber as Najim Laachraoui, a suspected bombmaker for the Paris attacks.
Khalid El Bakraoui blew himself up on the train, while Ibrahim El Bakraoui and Laachraoui died in the airport.
Laachraoui's younger brother said Thursday he was sad and overwhelmed over what his sibling did.
The 20-year-old Mourad Laachraoui told reporters that "I feel bad, that's all -- scared and saddened." He said the family had no contact with Najim since he left for Syria in 2013.
Najim Laachraoui is also suspected of having made bombs used in the Nov. 13 attacks that killed 130 people in Paris.
His brother described him as "a nice boy -- especially intelligent," who read a lot and practiced the martial art of taekwondo for a while like he does. He described their family as a practicing Muslim household, but said he couldn't say what put his brother on the path to violent extremism.
He said that "I'm no psychologist, no idea."
It is clear that some of the Brussels attackers had been on the run from authorities in France and Belgium but were still able to hide in safe houses, assemble bombs and carry out linked attacks.
"If you put all things in a row, you can ask yourself major questions," about the government's performance, said Interior Minister Jan Jambon, who along with Geens had tendered his resignation.
Notable among the questions were those raised by Turkey's announcement it had warned Belgium last year that one of the Brussels attackers, Ibrahim El Bakraoui, had been flagged as a "foreign terrorist fighter."
But Prime Minister Charles Michel asked Jambon and Geens to stay on, given the current challenge the government is facing.
Turkey said Wednesday that Ibrahim El Bakraoui was apprehended in June 2015 near Turkey's border with Syria and deported to the Netherlands. He was later set free by the Dutch for lack of proof of his involvement with jihadis.
Geens appeared on a Belgian TV news show and was asked who was to blame for the failure to follow up on the Turkish warning.
"It is clear it is not one single person, but it is true that we could have expected from Ankara or Istanbul a more diligent communication, we think, that perhaps could have avoided certain things."
"Our own services should perhaps have been more critical about the place where the person had been detained," he added, referring to Turkey's border area with Syria.
"When someone is arrested there in a city few people know, it is clear enough for insiders that it could be a terrorist," Geens said. "Here, though, he was not known as a terrorist. It is the only moment we could have linked him to it. And that moment, perhaps, we missed."
The justice minister acknowledged that "we have to be very self-critical."
But Geens added that "such events have also happened in nations with the best intelligence services in the world," pointing to the Sept. 11, 2001, attacks in the United States.
Terrorism expert Claude Moniquet told CBS News intelligence agencies have to up their game, and fast. He estimated there may be "dozens" of potential suicide bombers in Europe.
Authorities had been unable to find Salah Abdeslam, one of the Paris ringleaders and described as one of Europe's most wanted men, until a breakthrough led them to a Brussels apartment where he was arrested Friday.
The intelligence shortcomings have prompted European authorities to once again call for quicker and more efficient intelligence cooperation.
Rob Wainwright, the head of Europe's police agency Europol, said his agency is trying to make sure investigators have access to needed information.
"You have a fragmented intelligence picture but we're trying to help with that," he said. "Our databases contain thousands of names of suspected foreign fighters which have been submitted by member states, and even the United States. But we also have records on arms smuggling, money laundering, forgery and other elements which are particularly relevant given that many of these guys had petty crime backgrounds."
He said the threat goes beyond France and Belgium and that it is impossible to reduce it to zero.
"We are looking at large numbers of foreign fighters who have returned as potential terrorists," he said. "And we are faced with a strategic decision by the Islamic State to aggressively target Europe. These are all very challenging dimensions. As for how large the community is and who has been sent back - that is the golden question."
The federal prosecutors' office said Khalid El Bakraoui had rented a house used as a hideout for the Paris attackers, and that he had been hunted by police since December.
Also Thursday, Abdeslam was summoned to court in Brussels. His lawyer, who had initially vowed to fight extradition to France for the Paris attacks, said he now wants to be sent there as soon as possible.
Abdeslam evaded police in two countries for four months before his capture, and the attackers in Brussels may have rushed their plot because they felt authorities closing in.
Abdeslam's lawyer, Sven Mary, told reporters that Abdeslam "wants to explain himself in France, so it's a good thing." Mary said the extradition process should be completed by mid-April.
While Belgium lowered its threat level, "the danger has not gone away," said Paul Van Tigchelt, the head of the terror assessment authority.
Nevertheless, several hundred people gathered at a makeshift memorial to the victim in Brussels' central Place de La Bourse. They sang peace songs, took selfies and wiped away tears.