Last Updated Jan 17, 2015 9:32 AM EST
BRUSSELS -- Soldiers fanned out to guard possible terror targets across Belgium Saturday, including some buildings within the Jewish quarter of the port city of Antwerp. It was the first time in 30 years that authorities used troops to reinforce police in Belgium's cities, and came a day after anti-terror raids netted dozens of suspects across Western Europe.
Intelligence sources told CBS News Friday that a manhunt was underway for three people in Belgium trained by the Islamic State of Iraq and Syria, or ISIS, in Syria.
CBS News correspondent Charlie D'Agata reports from Antwerp, Belgium, that the suspects are thought to be heavily-armed and battle-ready.
Belgian federal magistrate Eric Van der Sypt told D'Agata he could not confirm that all of the most dangerous suspects had been caught.
"There's still an investigation going on," Van der Sypt told D'Agata. "... We are proceeding as fast as possible."
As a precaution, Jewish schools have been closed. Security has been beefed up around government buildings.
In an interview broadcast Saturday on Belgium's VRT network, Belgian Defense Minister Steven Vandeput said soldiers could be deployed to protect certain embassies and some buildings within Antwerp's Jewish quarter. Belgium has increased its terror warning to 3, the second-highest, following the anti-terror raids of Thursday which left two suspects dead.
Van der Sypt said Friday the suspects were within hours of implementing a plan to kill police.
On Saturday, French media reported that two Frenchmen with suspected ties to Al Qaeda in the Arabian Peninsula were arrested in Yemen. Intelligence sources have told CBS News one of the brothers who attacked the offices of the French satirical magazine Charlie Hebdo spent "several months" training with the terror group in Yemen.
In France, an official disclosed that slain gunman Said Kouachi had been quietly buried.
After an initial refusal, the mayor of Reims said he was forced to backtrack and allow the burial.
Mayor Arnaud Robinet said the government had insisted he allow the elder Kouachi brother to be buried in Reims because according to French law residents of a town have the right to be buried there.
"He was buried last night, in the most discrete, anonymous way possible," Robinet said in an interview on French television channel BFM TV. Robinet said he didn't know where Kouachi was buried in the cemetery, which he didn't identify.
Kouachi and his brother Cherif were killed by French counterterrorism police Jan. 9 after they killed 12 people at the offices of Charlie Hebdo. Cherif Kouachi is to be buried in Gennevilliers, a suburb of Paris where he lived, the city said in a statement Friday.
Authorities said a third gunman, Amedy Coulibaly, killed five people including four hostages at a kosher market in Paris before he was killed by police. There has been no word of plans for his burial.
French, German, Belgian and Irish police had at least 30 suspects behind bars on Friday and in Brussels, authorities said a dozen searches led to the seizure of four Kalashnikov assault rifles, hand guns and explosives. Several police uniforms were also found, which Belgian authorities said suggested the plotters had intended to masquerade as police officers.
The seizures followed an anti-terrorism sweep on Thursday in and around Brussels and the eastern industrial city of Verviers in which two suspects were killed in a firefight and a third wounded. Authorities said the follow-up operation netted several returnees from Islamic holy war in Syria.
Authorities have said there was no apparent link between the foiled plots in Belgium and last week's terror attacks in Paris on the newspaper and a kosher supermarket.