Obama mourns temple attack victims

US President Barack Obama said he and First Lady Michele Obama had been "deeply saddened" to learn of a shooting that left at least seven people dead at a Sikh temple in Wisconsin.

"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," he said, in a White House statement.

Earlier, police in the Wisconsin town of Oak Creek outside Milwaukee, said a gunman had opened fire on worshippers at a suburban Sikh temple. A police officer shot the attacker, but not before another six people were dead.

"Michelle and I were deeply saddened to learn of the shooting that tragically took so many lives in Wisconsin," Obama said.

"At this difficult time, the people of Oak Creek must know that the American people have them in our thoughts and prayers, and our hearts go out to the families and friends of those who were killed and wounded.

"My administration will provide whatever support is necessary to the officials who are responding to this tragic shooting and moving forward with an investigation."

Sunday's mass shooting was the second to rock America in less than three weeks and will increase pressure on Obama and his opponent Mitt Romney to address the issue of gun control before November's presidential election.

Romney also issued a statement of condolence.

"Ann and I extend our thoughts and prayers to the victims of today's shooting in Wisconsin. This was a senseless act of violence and a tragedy that should never befall any house of worship," he said.

"Our hearts are with the victims, their families, and the entire Oak Creek Sikh community. We join Americans everywhere in mourning those who lost their lives and in prayer for healing in the difficult days ahead."

Last month, a gunman burst into a movie theater in Aurora, a suburb of Denver Colorado and fired into the audience, killing 12 people and wounding dozens more.