An argument at a nightclub in a popular tourist area spilled out to the streets early Sunday, erupting into fighting and gunfire in which two people were killed and a third was wounded, authorities said.

Detectives were still sorting through details and trying to determine a motive, but police Capt. Michael Young said there were 50 to 75 witnesses. There were no immediate arrests.

"There was an argument, some type of disturbance in the night club," Young said. "It was closing, whether security pushed them outside or not, we don't know."

The argument spilled into the street outside Milwaukee's Vision club, he said, and about 15 people pushed, shoved and exchanged punches until shots were fired by as many as two gunmen.

Two men, ages 22 and 29, died after being shot multiple times, Young said. A third man, also 22, was shot and taken to a hospital.

Club employees locked the door and fled, he said.

A call to the club Sunday was not answered.

The club is on Old World 3rd Street, a tourist spot along the Milwaukee River.

"It's a good area, a safe area of Milwaukee," Young said. "We had not had any homicides there in the last 2 1/2 to three years."