While the name of the alleged gunman, who opened fire inside a Gurdwara in Wisconsin killing six people and critically injuring three others on Sunday morning has not been released yet, Thomas Ahern, a spokesman with the ATF's Chicago division, described him as a white male roughly 40 years of age.
The motive of the shooting has not been determined yet, even as security authorities late Sunday surrounded a duplex in Cudahy neighbourhood, where the shooter apparently lived.
A law enforcement said the gunman was dressed in a white T-shirt and black tactical-style pants, which had several pockets for holding ammunition magazines. He was armed with a single handgun, the official said.
Though the name of the gunman was not released but police say they have a tentative ID and were searching his home. The location was not disclosed.