Gunmen killed four police in southeast Nigeria, an official said on Wednesday, the latest attack in the restive region where dozens of officers have died this year.
In the dawn attack on Tuesday, gunmen stormed into a police station in Enugu state and opened fire, police spokesman Daniel Ndukwe said.
Parts of the building were set on fire, he added.
"Four of the operatives, who sustained severe gunshot injuries, were later confirmed dead in the hospital," he said.
A number of the attackers were shot and injured but managed to escape, Ndukwe said, appealing to residents for information that would lead to the arrest of the armed men.
In neighbouring Ebonyi state, a police officer also died after a hand grenade strapped on his belt accidentally detonated on Tuesday.
"The command is mourning the inspector who died in this unfortunate incident," police spokeswoman Loveth Odah told AFP.
Also on Tuesday, police repelled an attack on a station in Owerri, the Imo state capital.
Last month, gunmen raided the Imo state police headquarters and a prison and freed over 1,800 inmates.
No group has said it was behind the attacks but the Indigenous People of Biafra (IPOB), a proscribed separatist group demanding an independent state, is active in the region.
IPOB has several times denied responsibility for recent attacks.