Two people were killed and at least five others injured in a shooting at a Chicago nightclub early Saturday, police said.

The shootings at Cafe Allure (search) on the city's North Side occurred around 3 a.m. when several patrons, who had left a private party on the second floor of the club, returned and demanded to enter the main room on the first floor, said police spokeswoman Laura Kubiak.

"The main room was closed and the employees were cleaning and said, 'You can't come in,"' said Kubiak. "The individuals began firing into the club."

The Cook County (search) medical examiner's office had not released the identities of the victims Saturday morning.

A number of injured patrons drove themselves or were driven by friends to hospitals for treatment, police said.

At least one patron was in critical condition on life support at Northwestern Memorial Hospital (search), Kubiak said. The man had no identification on him when he was brought in, and authorities were still trying to determine his identity, according to a hospital spokesman.

Police were interviewing witnesses, but no one was in custody Saturday morning. Kubiak said she did not know how many people opened fire on the club or how many shots were fired.

The club, where DJs play lounge, jazz, house and hip-hop music, is located about 4 miles northwest of downtown Chicago.