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.

'Terrorist-type incident'

President Barack Obama spoke of his sadness at the shooting, which comes just over two weeks after a gun massacre left 12 people dead at a Colorado cinema.

In today's society, I don't think there's any place that's free from idiots Mark Honadel, Local politician In Pictures: Sikh temple shooting

Hundreds of people turned out for an impromptu candlelit vigil in the nearby city of Milwaukee for the victims of the temple shooting on Sunday evening.

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.

'Shot in face'

He said the gunman had opened fire on one of the first officers to arrive at the scene, as the officer tended to a victim outside the temple.

Image caption Distraught family members gathered outside the temple waiting for news

The policeman was shot multiple times, before a second officer exchanged gunfire with the suspect, fatally shooting him, added Chief Edwards.

At least three critically injured men were being treated at Milwaukee's Froedtert Hospital, said officials at that facility.

They included the shot police officer, although he was expected to survive, said Chief Edwards.

Local news station WISN 12 reported that one of the injured had gunshot wounds to the chest and abdomen, the second had shots to the face and the third had gunshot wounds to the neck.

Oak Creek is a town of about 30,000 people in the south-east corner of the state.

'Insanity'

The website for the temple says it opened in 1999 and now has a congregation of 350-400. Sunday morning was the busiest time of worship, members of the congregation said.

Devendar Nagra, whose sister escaped injury by hiding in the temple's kitchen, told the Associated Press: "We never thought this could happen to our community. We never did anything wrong to anyone."

Suni Singh told Newsradio 620 WTMJ that he had spoken to a friend inside the temple at the time.

"My friend called and said, 'I heard the shot, and two people falling down in the parking lot.' He saw the shooter reloading the gun," Mr Singh said.

Darshan Dhaliwal, who identified himself as a leader at the temple, told the Milwaukee-Wisconsin Journal Sentinel: "This is insanity."

Sikhism at a glance Sikhism is a monotheistic faith founded more than 500 years ago in South Asia

Observant Sikhs do not cut their hair; male followers often wear turbans and do not shave their beards

The faith has about 27 million followers worldwide. There are up to 500,000 Sikhs in the US, where they have sometimes been confused with Muslims

In Sept 2001, an Arizona gas station owner, Balbir Singh Sodhi, was shot dead by a man said to be seeking revenge on Muslims for 9/11

President Obama said he was "deeply saddened" by Sunday's incident.

"Our hearts go out to the families and friends of those who were killed and wounded," he said in statement released by the White House.

"As we mourn this loss which took place at a house of worship, we are reminded how much our country has been enriched by Sikhs, who are a part of our broader American family."

Local politician Mark Honadel called the attack "craziness".

The state representative told CNN: "Unfortunately, when this type of stuff hits your area, you say to yourself, 'why?' But in today's society, I don't think there's any place that's free from idiots."