The Federal Bureau of Investigation (FBI) said on Sunday it had joined a probe of a shooting at a suburban Sikh gurudwara in Oak Creek, Wisconsin, that left seven people dead, including the gunman.
"The FBI is working closely with the Oak Creek police department and other local and federal agencies to investigate today's shooting incident," FBI Milwaukee special agent in charge Teresa Carlson said in a statement.
Police have not yet assigned a motive to Sunday's shooting spree at the temple, but many Sikhs have endured taunts or violence since the September 11, 2001 attacks.
Carlson said this remained an active investigation in its early stages.
"While the FBI is investigating whether this matter might be an act of domestic terrorism, no motive has been determined at this time," she said.
Carlson said the thoughts of FBI agents were with those affected by the shooting, particularly with an officer who was wounded in the line of duty to protect others.