Seven policemen were killed in a series of attacks on security installations in Nigeria's oil-rich Rivers state, police said Saturday.
Southeast Nigeria has seen a surge in attacks by gunmen targeting police and other security forces in the past few months in a region where separatist tensions are on the rise.
"The incident which led to death of seven policemen occurred last night at about 19:30," Nnamdi Omoni, police spokesperson in Rivers state said in a statement about the three attacks Friday.
"Unknown gunmen driven in two branded Hilux vans attacked the special check point at Choba bridge, (and) in a surprise attack killed two policemen on duty."
He said the same gunmen attacked Rumuji police station, killing two officers and burning a police patrol vehicle.
"Two of the attackers were fatally wounded and died on the spot," he added.
A third attack took place at Elimgbu Police station, Omoni said, where gunmen killed three officers.
The police spokesperson said a manhunt was underway to find the perpetrators who escaped.
Security was "strengthened in all the police formations in the State, including other critical public and private infrastructure" he added, without giving further details.