TOKYO, Nov 7 (Reuters) At least nine people were killed, at least 20 injured and others trapped under rubble when a tornado hit northern Japan on Tuesday, local officials said.

Officials said the tornado demolished two prefabricated buildings at a construction site, about eight private houses and a factory.

Two people were still missing, said an official at the fire department in Engaru, on the northeastern part of Japan's northern island of Hokkaido. He added that rescue efforts were being hampered by rain and a power blackout.

The official said 15 people had been taken to hospital by ambulance and others had gone by themselves. About 40 workers had been employed at the construction site, he said.

Television footage from the town of Saroma showed workers trying to rescue those still trapped in the collapsed prefabricated buildings, which a town official said were being used as temporary dormitories for construction workers.

Fire engines and ambulances were at the site, where crushed cars could be seen along with lumber and other scattered debris.

TV showed several houses reduced to rubble and at least one home with its roof torn off.

REUTERS BDP BD1320