FREETOWN (Reuters) - Power hoses and AK-47 assault rifles have succeeded where Sierra Leone's snake-charmers failed by removing 400 cobras and vipers that overran a police station.

Authorities in the southern district of Bo called in police, army and fire fighters after the snakes scared away police officers and residents reporting crimes.

"We have forced water into the building and some of the snakes trying to escape were shot by our men carrying AK-47s," said Brima Kontu, head of the police station in Gerihun.

About 250 of the estimated 400 snakes who had made the station their home have been killed.

"Hopefully the combined force will be able to free the house from the snakes by next Tuesday," Kontu told Reuters.

Sierra Leone is slowly recovering from the effects of the 1991-2002 civil war and villagers frequently have run-ins with wild animals in areas of the country that were deserted during the years of fighting.

(Reporting by Christo Johnson; Writing by David Lewis; Editing by Robert Woodward)