At least seven people, including a gunman, have died in a shooting at a Sikh temple in Wisconsin in the US.

The attacker "ambushed" a policeman at the scene, shooting him multiple times, before a second officer returned fire, killing the gunman, said authorities.

The shot officer was among three men critically injured in the attack in Oak Creek, suburban Milwaukee.

Later local TV showed police vehicles at another suburb, near what is believed to be the gunman's home.

Reports said the FBI and a bomb squad had gone to search the building, in Cudahy, about 2.5 miles (4km) north of the temple, and had evacuated several blocks.

Police said they believe there was only one shooter, despite initial witness reports of more than one gunman. 

At a press conference, Oak Creek Police Chief John Edwards said they were treating the attack as a "domestic terrorist-type incident", and that the FBI would take over the criminal investigation.

He said he could not release any information about the shooter, who local media reports said was a white male aged about 40.

Women and children hid in closets as the gunfire erupted shortly before 10:30 local time (15:30 GMT) on Sunday.

Four people were dead inside the temple and three outside - including the gunman, said the authorities.

"The best information is that there was only one gunman," said Chief Edwards.