Three cyclists died in hit-and-runs last week in New York City, marking the grimmest week yet in an already deadly year for bike riders across the city.

Mamadou Diallo, 40, of Brooklyn, was struck by a BMW just before midnight Thursday on Avenue I in Brooklyn’s Flatlands neighborhood during a torrential downpour. He had been on an e-bike; the driver fled the scene, according to the Police Department.

Mr. Diallo had come to New York from Guinea, his friend, Abdoulaye Barry, said, calling him “a gentle person” and saying he was working making deliveries for DoorDash when he was struck and killed.

DoorDash did not immediately respond to a request for comment.

Two days earlier, on Aug. 18, Paulina Tec Choc, 29, of Queens, was stopped on an e-bike at the intersection of Jamaica Avenue and Cypress Hills Street in Brooklyn just before 6 a.m. when the driver of a Ford pickup truck struck and killed her, then fled the scene, the police said. She had a husband and an 8-year-old daughter, according to a GoFundMe organized after her death.

That same day, Angelo Camara, 51, a mechanic and a father of five from the Bronx, was hit by a BMW while cycling on Bruckner Boulevard in the South Bronx. The driver of that car fled the scene on foot, the police said.

All three cyclists were coming or going from work when they died,according to friends and advocates. No arrests have been made in any of the three deaths.

Seventeen cyclists, riding both e-bikes and traditional bicycles, have been struck by vehicles and killed so far this year, according to data from the Police Department and the city Department of Transportation, compared with 10 deaths at the same point last year. A total of 20 cyclists died in traffic collisions last year, according to the data.

“This is a crisis,” said Alexa Sledge, the spokeswoman for Transportation Alternatives, which is organizing a protest in front of City Hall on Wednesday to call attention to the rise in cyclist fatalities across New York.

“The fact that three were killed in just three days is a call to action for every elected leader in New York City,” Ms. Sledge said.

City Hall did not immediately respond to a request for comment.

The increase in cyclist deaths comes after a year in which pedestrian deaths and traffic fatalities in the city were at a record low. Mayor Zohran Mamdani, himself an avid CitiBike user, has worked to revive plans for bike lanes that were quashed under former Mayor Eric Adams. Mr. Mamdani also took to social media last week to highlight bike safety and to vow that he would start wearing a helmet.

At Wednesday’s protest, which Transportation Alternatives is organizing in partnership with Families for Safe Streets, cyclists plan to rally for a “systematic, comprehensive safety plan,” Ms. Sledge said, that calls for more bike lanes, better lighting, curb extensions and other improvements across all five boroughs. Demonstrators will then lie down in a simulated “die-in” to bring attention to the risks they face while cycling.