Two Libyan soldiers and an American teacher were shot dead in Benghazi on Thursday, medical and security officials said.
A third soldier, who was attached to military intelligence, died when a bomb placed under his vehicle blew up, a security official said.
The soldiers were the latest of dozens of security personnel to be gunned down in recent weeks, security officials said.
The dead US citizen taught chemistry at the city’s international school, security services spokesman Ibrahim al-Sharaa said, and was shot dead as he was taking his morning jog.
The violence rocking the city, which was the cradle of the NATO-backed rebellion against veteran dictator Muammar Gaddafi, is largely blamed on jihadi groups that have mushroomed since he was toppled and killed in 2011.
Chief among them is Ansar al-Sharia, a jihadi group accused of the September 11, 2012 attack on the US consulate in Benghazi that killed ambassador Chris Stevens and three other Americans.
Further east, in the Islamist bastion of Derna, residents on Thursday staged new demonstrations against what they say is anarchy in the city and to demand a police and army presence.
On Monday, unknown gunmen fired on protesters in Derna, leaving one person dead and seven hurt, according to an updated toll given by a medic on Thursday.
Like Benghazi, Derna has in recent months seen a wave of killings of members of the security forces and the judiciary in attacks blamed on Ansar al-Sharia.
The group implicitly denied responsibility for Monday’s attack on protesters in Derna.
“Opening fire with live rounds on protesters … is a dangerous thing,” the group said in a statement received on Thursday by AFP.
Prime Minister Ali Zeidan announced on Wednesday that preparations were under way to send troops to Derna, where law and order is almost non-existent.
Libya’s new authorities have tried in vain to integrate former rebels who helped topple Gaddafi into the regular armed forces, with many militias carving their own fiefdoms, each with its own ideology and regional allegiances.