A night of Halloween revelry turned bloody as a rash of shootings around the city left eight people injured overnight.

During one shooting incident in Union Square, amidst crowds of costumed New Yorkers celebrating the holiday, four people were injured by gunfire and a ninth victim was seriously hurt after he was stabbed.

The incident occurred shortly after midnight, not long after the annual Halloween parade had disbanded across town. Police said a group of young people had been involved in an argument that began at the corner of 14th Street and the south end of Union Square, and moved across the park.

“The victims may have some gang membership,” the police commissioner, Raymond Kelly said today.

He added that the fifth victim, who was stabbed, was in serious condition. The others were at Bellevue Hospital in stable condition.

Two other shooting incidents happened in Brooklyn. In the first shooting, police discovered a 20-year-old man with a gunshot wound to his chest at around 7:30 p.m. yesterday in the lobby of an apartment building in East Flatbush.

In a second multiple shooting, in Bedford-Stuyvesant in Brooklyn this morning, three men were injured, with one left in critical condition after being shot in the back, police said.

No arrests had been made as of this evening.