Five people have died as a crane toppled off a 25-storey residential tower in Canada, police say.

Four construction workers on the ground were killed in the accident on Monday in Kelowna, 390km east of Vancouver, police Inspector Adam MacIntosh said.

The crane operator hasn’t been found but police believe his body is buried in the rubble, MacIntosh said.

The upper portion of the crane smashed into a neighbouring building.

Jonathan Friesen, head of the Mission Group, the development company building the structure, said he did not know what caused the crane to fall.

The collapse knocked out power for most of the city’s downtown core and forced an evacuation of the surrounding area.