"Your mother loves the water, doesn't she?" Chinnarie's grandmother, Cynthia Thomas, 49, asked him on Friday. The boy looked up and smiled.

His mother, Fatima Gordon, 28, was killed in a shooting on Clarkson Avenue in Prospect-Lefferts Gardens on Thursday night. The police said three others, including a 13-year-old boy, were injured. At the time of the shooting, just after 9 p.m., the block was filled with stopped traffic, the sidewalks were packed with pedestrians, and dozens of residents sat and chatted on porches and stoops, enjoying the warm evening, neighbors said.

The police said a man rode through the crowd on a bicycle and opened fire, striking and killing Ms. Gordon.

"There were so many cars in the street, nobody could move," said Nogga Schwartz, 27, who was on the sidewalk moments before the shots were fired.

The Police Department, which at first said Ms. Gordon, whose birthday would have been Sept. 4, was 29, has not said whether it has any suspects in the case.

In the midst of this busy neighborhood, violence has been rampant all summer, residents said.

"There's been a shooting or a stabbing on this block every other night for the last two weeks," said Richard Nettles, 54, who has lived on the block since 1972. "I've stopped going outside at night. If I need something from the store, I just wait until the morning."

On Thursday night, Ms. Thomas needed groceries, but because of the recent violence, she encouraged her oldest daughter, Ms. Gordon, to stay home. But Ms. Gordon, after watching her son and a brood of her younger half-brothers, half-sisters and cousins in the apartment all day, was eager to go out.

She was walking behind her son, her mother and four other children in the family, pushing a shopping cart, when the shots were fired, Ms. Thomas said. Ms. Thomas dived. Looking behind her, she saw blood and knew that Ms. Gordon had been hit. She told Chinnarie to crawl toward her and not look back.

"Keep looking at grandma," Ms. Thomas said she told the boy.

Once the children were out of the way, Ms. Thomas crawled back to Ms. Gordon, who was lying on her side in a growing pool of blood. Ms. Thomas held her daughter's head in her arms.

When Mr. Schwartz, a neighbor, arrived moments later, he touched Ms. Gordon's neck and felt a weak pulse. He asked her to blink if she could hear him. She blinked. Then she was gone, he said.

"It all happened so fast," Mr. Schwartz said. "I just kept wondering where the ambulance was."

Another victim, Aaron Munoz, 13, said he was riding his skateboard on the sidewalk ahead of Ms. Gordon and her family. When the shots were fired, he said, he ducked, ran into the lobby of a building, felt moisture on his back and realized he'd been grazed by a bullet.

He realized, "I think I got shot," he recalled.

A relative of his, Aliysa Ram, 23, was trading jokes with Ms. Gordon when the shooting started. She also took cover in a lobby and looked outside to see Ms. Gordon wounded on the street.

Violence in the neighborhood escalates toward the end of the summer, said Ms. Ram. "People get noisy and rowdy," she said.

Ms. Gordon and her mother had lived on this block of Clarkson Avenue, between Flatbush and Bedford Avenues, since 1990. Ms. Thomas said her daughter was well-known to longtime residents: her nickname was Chin, because her father was Chinese; she liked to dye her long hair different colors. For most of the summer, it had been bright green, said Stephanie Chanlatti, 29, Ms. Gordon's friend and neighbor, but about two weeks ago, she made it blond.

"She was quiet. She just liked to take the kids to Prospect Park and play," Ms. Chanlatti said.

She loved to swim, Ms. Thomas said, and hoped to take her family on a Disney cruise and eventually buy a house with a pool, someplace far from her dangerous block.

"She just wanted our family to be safe," she said, adding that her daughter had recently applied to several nursing schools.

Alex Vadukul contributed reporting.