“We have had a difficult and challenging year under Vision Zero,” said Polly Trottenberg, the city’s transportation commissioner, said on Sunday. “And as 2019 comes to a close, we want to make sure that this holiday season is a joyous and safe one for all New Yorkers.”

On Monday, city officials will announce plans to increase police enforcement efforts targeting commercial trucks, which were involved in four of the six pedestrian deaths last week.

Danny Harris, executive director of the transit advocacy group Transportation Alternatives, said on Sunday, “New York continues to lead on street design and street safety, but our processes are too slow and we still need more of our elected officials to stand up and fight for people over traffic.”

It is not unusual, city officials say, to see a spike in traffic deaths toward the end of the year, when there are fewer daylight hours and more pedestrians, cyclists and drivers are drawn out to the streets during the holiday season.

But the deaths of six people in only 72 hours was alarming.

On Wednesday morning, Lin Zhisheng, 67, was walking near Main Street in Flushing, Queens, when he was hit by a car as it turned into a parking garage. Later that day, Xue You, 75, was crossing 52nd Street in the Sunset Park area of Brooklyn when a 21-year-old driving a white Jeep made a left turn onto the street and hit her.

The following day around 3:30 p.m., a box truck driving down Third Avenue near Sunset Park hit an 85-year-old man, Brendan Gill, as he was crossing the street.

Hours later in the SoHo neighborhood of Manhattan, Katherine Miller, 26, was struck by a Ferraro Foods truck when it reversed into her on Broadway, near Howard Street. She was pronounced dead at the scene.