Five men were shot to death and a sixth was seriously wounded as they played cards early Saturday in a basement social club in Boston's Chinatown section, police said.

Police refused to provide details on whether the shootings involved only those found in the club shortly after 4 a.m. or whether suspects were being sought.Boston Mayor Raymond Flynn said police had received information several days ago that some young Asian-American men had formed gangs but that the groups had no leadership.

"When you have leaderless gangs, that's a serious issue, a serious problem," the mayor said.

The wounded man was reported in critical condition at a local hospital, which police officers refused to name for his own protection.