Two of the victims are badly wounded, the authorities said.
The shooting took place around 5:20 p.m. on the boardwalk near Brighton Sixth Street, the Fire Department said.
The shooting unfolded on a day when a mini-heat wave and a school holiday sent hordes of people to Coney Island and Brighton Beaches, which were teeming with beachgoers — many of them teenagers — trying to escape temperatures approaching 100 degrees.
Saya Suzuki, 30, was just about to sit down inside a boardwalk restaurant with her six-year-old daughter, Sonya, when the shooting began just outside. Ms. Suzuki said she heard about six shots, then grabbed her daughter and saw two teenagers run by her.
“I just picked up my daughter and got away from the bullets,” she said. “It happened so quickly and I had to protect my daughter.”
As the police roped off the scene and combed the boardwalk, Ms. Suzuki, still terrified, stayed in the restaurant for two hours waiting for her husband. She said she had noticed other incidents earlier in the day that worried her.
“I think some gang things were happening because we heard some shots one hour earlier,” she said.
The two most seriously injured people, a man and a woman, were taken to Coney Island Hospital, where they are in critical condition, the Fire Department said. A second man, whose condition was not available, was also taken to Coney Island Hospital, the department said.
A fourth victim, a man, was in serious condition at Lutheran Medical Center, the Fire Department said. A fifth victim’s injuries were not life threatening, the police said.
There have been no arrests, the police said.