Five foreigners -- one American, one French citizen, and three people from Tajikistan -- were killed in the attack, Essam al-Naas said. Five Libyans were killed.
The Libyan branch of ISIS claimed responsibility for the attacks, and released photos of the two gunmen, it said had carried out the attacks as Abu Ibraheem Al-Tunsi and Abu Sulaiman Al-Sudani. Their naming convention indicates that the men were of Tunisian and Sudanese origin, respectively.
Al-Naas said it appears the attackers were Libyans.
American contractor David Berry was among the people killed in a terrorist attack at the Corinthia Hotel in Tripoli, Libya, on Tuesday, according to Cliff Taylor, chief executive officer of Crucible, a security firm where Berry was working.
The FBI is expected to open an investigation into the incident, two U.S. officials told CNN. A State Department official confirmed the death of a U.S. citizen, but would provide no further information.
A French citizen was among those killed, according to the French Foreign Ministry.
Al-Naas earlier said at least two Libyan security personnel had been killed in the attack and that three gunmen were holed up in the hotel.
An online group that supports ISIS said the attack was carried out in the name of Abu Anas al-Libi.
Al-Libi was an alleged al Qaeda operative accused of involvement in the bombing of U.S. embassies in Africa. He was captured by U.S. special forces in Libya. He died in a U.S. hospital this month.
A spokesman for the Corinthia Group in Malta told CNN there had not been a hostage situation in the hotel, as some reports suggested.
"We are trying to take possession of the hotel back to assess the damage," he said, but Libyan security forces were not yet allowing that.
Explosion then gunshots
The attack began when militants detonated a car bomb in the parking lot of the hotel. The gunmen then shot their way into the hotel.
Guests were evacuated to safety, however. The five-star hotel is popular among government officials, some of whom reside there.
A witness to the events told CNN that all roads leading to the Corinthia Hotel had been sealed by security forces.
People were warned to stay away, the witness said, adding that there had been exchanges of gunfire.