Why Would Anyone in the U.S. Shoot Up a Sikh Temple?

A single attacker entered the Sikh Temple in the Oak Creek suburb of Milwaukee, WI, and killed six worshippers before he was killed in gunfire with police, outside the building.
So far, no one knows why he attacked, but plenty of leftists, who wouldn’t be able to distinguish between Sikhs and Muslims, are blaming it on the Tea Party and calling it an Anti-Muslim or Racist Act.
Pharmer supposes that the  attacker must have been thoroughly Bonkers, as well as sociopathic.

Among the victims are Parkash Singh, and Satwant Kaleka (president of the temple). So far the most info is available at Milwaukee Journal Sentinel. That news source reports that there are about 3000 Sikh families in S.E. Wisconsin who gather at the Religious Society in Brookfield and the Sikh Temple of Wisconsin in Oak Creek. The paper recalls a similar incident in 2005 when Terry Ratzman attacked a gathering of the Living Church of God in Brookville, and killed 7 people as well as himself.

Prayers for the victims of the massacre at the Sikh Temple  and for their families.