LAGOS, May 9 (Xinhua) -- Nigerian police have confirmed seven policemen were shot dead following gunmen attacks on police stations and checkpoints in the country's southern state of Rivers.

In a statement issued in Port Harcourt, the state capital on Saturday night, Nnamdi Omoni, a spokesman for the police in Rivers, described the attacks as "unprovoked and mindless" as a group of gunmen attacked a security checkpoint and two police stations in the state on Friday evening.

The gunmen in two Hilux vans launched a surprise attack on a police check point at a bridge in Port Harcourt, killing two policemen, and later they attacked a police station in Emohua local government area, killed two policemen on duty, said Omoni.

"A stiff resistance by other police officers prevented the hoodlums from gaining access into the police station," said the police spokesperson.

According to Omoni, the police also lost three officers during the third attack of the same gunmen at a police station on Igwuruta road in Port Harcourt.

"The attack was resisted by our officers during a serious fire engagement that resulted in the gunmen abandoning their bullet-riddled Hilux van," he said.

He said the gunmen fled in a snatched Sienna bus and with various gunshot wounds, and two of the assailants were killed during the exchange of gunfire with policemen.

He said none of the police posts was burnt by the gunmen and five assault rifles were lost during the three attacks.

The spokesperson added operatives had launched a manhunt for the perpetrators with a view to apprehending the culprits and bringing them to justice.