Lebanese Interior Minister Raya Al-Hassan said Tuesday that a gunman was working alone when he went on a shooting spree that killed four security personnel in the northern city of Tripoli. Al-Hassan said the shooting by the man identified as a former ISIS member, Abdul-Rahman Mabsout, is a "lone wolf attack", and the situation is under control. She spoke to reporters in Tripoli, hours after Mabsout, riding a motorcycle, opened fire on police and army vehicles in the city, killing two police officers and two soldiers before breaking into a residential building and hiding there. He later blew himself up by detonating an explosive belt when confronted by troops. The attacker had earlier been in jail on charges of ISIS membership, a source said. The rare shooting, which began late Monday, shook the coastal city on the eve of the Eid al-Fitr holiday, which marks the end of the holy month of Ramadan. Prime Minister Saad Hariri extended his condolences to the families of the dead and said all measures must be taken to protect Tripoli and "weed out any remnants of terrorism". Al-Hassan described the attack as "a new form of terrorism". "Can I tell you we can curb it 100 percent? We cant curb it. Countries that are perhaps more advanced than us have not been able to," she told a press conference. Internal Security Forces chief General Imad Othman, accompanying her, said the agency constantly keeps tabs on suspects and sleeper cells. "But when someone reaches a level of desperation in some cases, and carries out a crazy action, this leads us to not know about him (ahead of time)," he told reporters.