TUNIS, Tunisia -- One of the two gunmen who killed 20 tourists and others at a prominent Tunisian museum was known to intelligence services, Tunisia's prime minister said Thursday, but no formal links to a particular terrorist group have been established.
Police launched an intensive manhunt following the attack for accomplices, and a statement from the president's office said nine people linked to the gunmen had been detained Thursday, according to the French news agency AFP.
"The security forces were able to arrest four people directly linked to the (terrorist) operation and five suspected of having ties to the cell," AFP quoted the statement as saying.
The dramatic attack at the National Bardo Museum on Wednesday was the worst in years in Tunisia and a blow to its young and fragile democracy. It also threatened new troubles for the tourism industry, which brings throngs of foreigners every year to its Mediterranean beaches, desert oases and Roman ruins -- and had just started to recover after years of slump.
The death toll rose by two Thursday morning, as the Health Ministry said 20 tourists were killed rather than the 17 confirmed Wednesday. Three Tunisian nationals also were killed. But there as also some good news, as CBS News correspondent Allen Pizzey reported, two Spanish tourists were found still hiding inside an office at the museum Thursday morning, apparently unharmed. They were taken to hospital for medical checks.
In an interview with France's RTL radio, Prime Minister Habib Essid said Tunisia is working with other countries to learn more about the attackers, identified as Yassine Laabidi and Hatem Khachnaoui. They were killed by security services in a raid after they attacked the museum.
He said Laabidi had been flagged to intelligence, although not for "anything special."
Tunisia has faced scattered Islamic extremist violence. Twitter accounts associated with the Islamic State of Iraq and Syria (ISIS) praised the attack.
ISIS has shown a particular interest in Tunisia recently, releasing a video in December featuring three prominent Tunisian jihadists calling on their comrades in the group Ansar al-Sharia to pledge allegiance.
Ansar al-Sharia is one of the few Islamic militant groups to have a significant presence in Tunisia. There are groups of the same name in a number of other countries in the region, but links or coordination between the different Ansar al-Sharias has never been clear. Militants from Ansar al-Sharia in neighboring Libya were behind the 2012 attacks on U.S. diplomatic outposts in Benghazi that left U.S. Ambassador Christopher Stevens and three other Americans dead.
Reports in Tunisian media Thursday suggested the two men could have had links to the Uqbah Ibn Nafe'a brigade, believed to be the military branch of Ansar al-Sharia in Tunisia. The Tunisian Interior Ministry said Uqbah Ibn Nafe'a was linked to al Qaeda's North African franchise, al Qaeda in the Islamic Maghreb (AQIM).
The Uqbah Ibn Nafe'a brigade has claimed responsibility for almost all attacks in Tunisia in recent years, mainly targeting security forces.
According to statistics from the International Centre for the Study of Radicalisation and Political Violence (ICSR), Tunisian jihadists constitute the largest number of recruits who have joined ISIS and other groups on the chaotic battlefield of Syria.
According to official figures announced by the Tunisian Interior Ministry last June, there are at least 2,400 Tunisian jihadists fighting in the ranks of ISIS. ISCR put the total number of militants in Syria to have come from Tunisia as of the same time period at 3,000.
The Tunisian government warned last year that the number of jihadists wishing to join ISIS was on the rise, and the Interior Ministry said it managed to stop 8,000 youths from leaving the country to join the group.
Two cruise ships whose passengers had been among the victims pulled out of the port of Tunis early Thursday. MSC Cruises said nine passengers from the Splendida were killed, 12 injured and six unaccounted-for as its ship pulled out to the Mediterranean at sunrise. Another ship, the Costa Fascinosa, said 13 passengers had not returned on board when the ship left port overnight.
The 17 tourists killed included people from Japan, Italy, Colombia, Spain, Australia, Poland and France. Essid said two Tunisian nationals also were killed by the militants.
At least 44 people were wounded, including tourists from Italy, France, Japan, South Africa, Poland, Belgium and Russia, according to Essid and doctors from Tunis' Charles Nicolle.
Best1cruise spokesman Takao Ogawa confirmed that two of the three Japanese victims were part of a group tour of 23 tourists arranged by the company for MSC Excursions, but declined to release their identities. The tour joined the cruise from Genoa and was to continue to Paris. He said it was not immediately clear whether the group will continue traveling.
Best1cruise is preparing to arrange a flight for the victims' families if they wish to travel to Tunis.
The attackers, who wielded assault rifles, burst from a vehicle and began gunning down tourists climbing out of buses. The attackers then charged inside to take hostages before being killed in a firefight with security forces.
"I want the people of Tunisia to understand firstly and lastly that we are in a war with terror, and these savage minority groups will not frighten us," said newly elected President Beji Caid Essebsi in an evening address to the nation. "The fight against them will continue until they are exterminated."
Tunisians overthrew their dictator in 2011 and kicked off the Arab Spring that spread across the region. While the uprising built a new democracy, the country has also struggled with economic problems and attacks by extremists.
Now, reports CBS News' Pizzey, Tunisians will be left to worry whether they are being swept into the deadly whirlpool of terrorism and fundamentalism which has swept across other parts of North Africa.
"This is really very disappointing" one resident of Tunis told Pizzey. "It makes all the Tunisian people very sad, especially since Tunisia was just beginning to get on the right track."