What was supposed to be a fun summer block party in Sunset Park turned deadly this weekend when someone shot and killed a man in the middle of the festivities, police said.

Neighbors told News 12 the party on 57th Street off 4th Avenue started like any other Saturday celebration — with drinks, food and music.

“Everybody was out, everybody was having fun, everybody was partying, barbecuing,” one neighbor said.

Victor Vizcaino, who lives on the block, said he was with his family when the shooting began.

“There were many people, including my family, outside eating and playing dominos,” Vizcaino said. “Things were winding down, cars were starting to come back onto the street, then before you knew it, four gunshots. People started running down the streets.”

Police identified the victim as 45-year-old Roberto Cuevas, a Sunset Park resident. NYPD sources say Cuevas argued with the shooter earlier in the evening.

Witnesses told News 12 the victim was lying on the ground after being shot in the back. Cuevas was taken to the hospital but died shortly after.

Police say no arrests have been made, and the investigation is ongoing.

“It was so crazy to see, the overwhelming feeling on the street was disbelief that someone would do this while kids and families were outside,” said Vizcaino.