A lone gunman killed four members of Lebanon’s security forces in the city of Tripoli on Monday night before blowing himself up, state media report.
Two police officers and two soldiers died after the man fired at a bank, a police station and an army vehicle.
He detonated an explosive vest after being surrounded in a flat by troops.
No group has said it was behind the attack, but the gunman is reported to have been a member of the jihadist group Islamic State (IS).
The army identified him as Abdul Rahman Mabsout, who LBC television said was detained when he returned from Syria in 2016 and was freed the following year.
Security had earlier been increased across the country in preparation for Eid al-Fitr, the festival marking the end of the Islamic holy month of Ramadan.
Interior Minister Raya Haffar al-Hassan tweeted her condolences to the victims’ families, saying: “The first night of Eid in Tripoli was very painful, but it’s over now. The security forces and the army paid a heavy price to maintain security of the city… May God have mercy on our martyrs.”
At a news conference on Tuesday, Ms Hassan described the shootings as a “lone wolf attack” and a “new form of terrorism”, Reuters news agency reported.
“Can I tell you we can curb it 100%? We can’t curb it. Countries that are perhaps more advanced than us have not been able to,” she added.
Tripoli has in the past been affected by deadly violence linked to the eight-year civil war in Syria, with clashes erupting between groups who support or oppose President Bashar al-Assad.
The city has also seen fighting between the army and Islamist militants.