Condemning the Wisconsin Sikh Temple shooting, in which a gunman killed six and critically injured another three on Sunday, hundreds of Sikhs protested in India on Monday.

An unidentified bald, white man in his forties opened fire just before prayer services began in the 5-year-old Sikh temple. The gunman, who reportedly had a tattoo of 9/11 attacks on one his arms, was later shot down by a police officers.

FBI has launched a probe into the shooting and has hinted that it could be an act of "domestic terrorism," while the Sikh community in the U.S believes it to be a crime of "hate and ignorance."

"We're treating this as a domestic terrorist incident," said the Oak Creek Police Chief John Edwards, as reported by Reuters.

The Sikh religion originated in India more than 500 years ago and it has over 25 million followers all over the world. The community members and various Sikh groups in India, concerned over the rising crime rates against the Sikh community, held a protest march in New Delhi, Jammu and other places in the state of Punjab.

The Indian Prime Minister Manmohan Singh condemned the attack. "I am deeply shocked and saddened to learn of the shooting incident that has resulted in the loss of precious lives and injuries to devotees attending a prayer service at a Gurudwara in Wisconsin, USA," said a statement released by his office.