The young man fatally stabbed in a gang-related attack near million-dollar Brooklyn homes Saturday was a “quiet kid’’ watching a local soccer game when violent menaces on mopeds rolled up, witnesses said.

Police on Sunday identified the fatal Dyker Heights victim as Manuel Estanislao Chox Choc, 21, from neighboring Bath Beach — and took a 16-year-old with suspected ties to a notorious Mexican gang into custody for his murder.

Law-enforcement sources said they believe that the stabbing was carried out by members of the Los Niños Malos gang, a Mexican street gang whose name means “Bad Boys” in Spanish.

The gang is well-known for terrorizing Brooklyn, having strongholds in Sunset Park and Bed-Stuy, sources said. 

The fatal brawl, which also left a 30-year-old man in critical condition with stab wounds, rocked the neighborhood around 2 p.m. inside Dyker Beach Park, cops and residents said.

“I saw a lot of cop cars and an ambulance car going over there,” said an ice-cream vendor, who was working in the park when the fight broke out, to The Post on Sunday. 

“I got scared. I heard screaming. Someone told me a young man is hurt over there,” she said. 

Tim Moeller, 59, said he was playing bocce when he saw the fight break out. 

He said that the two victims were watching a soccer game when menaces on mopeds rolled up and started the chaos. 

“There were two guys on a scooter. They were driving around here. They were the ones that initiated the problem,” Moeller told The Post. 

The thugs stabbed the pair, leaving them in the field before jetting off on their scooter, according to Moeller.  

“By the time anybody realized what happened, it was already over,” Moeller said. 

Chox Choc and the other stabbed man were rushed to Maimonides Hospital by EMS, where Chox Choc died. The 30-year-old man is in critical condition, according to authorities. 

A small memorial was erected by Sunday near the soccer field where the two were stabbed. 

The unidentified 16-year-old suspect was cuffed in connection to the crime Sunday evening, cops said. 

The teen suspect was charged with murder, attempted murder and criminal possession of a weapon, police said. 

Victim Chox Choc was described as a “quiet kid” by locals.

“I would just hear him talk about meeting up with family,” said Justin Rroku, 21, a neighbor.

Moped-riding scofflaws have been a consistent problem in the area, terrorizing Dyker Beach Park, residents told The Post. 

“These idiots always come through here in their mopeds,” Moeller said. “The guy in the Parks Department chased them out of here the other day.”

Miguel Cocom, 31, said he’s had some close encounters with the thugs while spending time in the park. 

“They come around here wearing ski masks,” Cocom said. “There’s always a group of about five in mopeds. They drive reckless.”

Moeller’s criticism for the young creeps was more direct. 

“They’re f—ing criminals,” he said.