Kenosha County Sheriff David Beth said authorities responded to the Great Lakes Dragaway in Union Grove around 7 p m after receiving reports about shots being fired.
The three men were shot by another man at point-blank range near a food vendor, Beth said at a news conference yesterday. No suspects were arrested and no one else was injured.
"They have no idea what happened, what caused this," the sheriff said after getting a statement from friends of the victims.
Two of the men died at the scene, and the third died while being transported to a hospital. Beth said at least two of the men were from Aurora, Illinois.
Union Grove is about 40.23 kilometers south of Milwaukee.