Two men — a Mercedes passenger and a bicyclist — were killed in a pair of crashes about a block apart and less than 12 hours apart in Williamsburg, Brooklyn, cops said. 

The first victim, Alex Caba-Guitierrez, 33, was riding in the backseat of a Mercedes-Benz around 9:45 p.m. Monday when the driver whizzed through a red light at the intersection of Harrison Avenue and Lorimer Street, authorities said. 

The motorist then rammed into an MTA bus, driven by a 31-year-old man, heading east on Lorimer Street, police said. 

The impact forced the bus to mount the sidewalk, striking a Citi Bike kiosk, before Guitierrez was catapulted from the Mercedes, cops said. 

The callous Mercedes driver took off, leaving his passenger on the ground. 

Guitierrez, who lives about a mile from the scene, was rushed to Bellevue Hospital, where he was pronounced dead. 

Meanwhile, the MTA bus driver was taken to Wyckoff Heights Medical Center, and a bus passenger to Interfaith Medical Center, where they were both listed in stable condition, cops said. 

The driver had not been caught by Wednesday.

Just before 8 a.m. the next morning — and about a block away — bicyclist John Paolicelli, 64, was knocked by one car’s door into the path of another vehicle, cops said.

Paolicelli was riding a bike east on Broadway near Lorimer Street alongside a 2022 Hyundai Elantra when a 2019 Honda Accord driver swung open his front door, which struck the cyclist, authorities said. 

Paolicelli then flipped into another lane, directly into the path of the Elantra, which ran over and pinned him, cops said.

The NYPD’s Emergency Service Unit responded and moved the Elantra, but it was too late.

Paolicelli had suffered severe head trauma and was unresponsive, cops said. 

Paolicelli, an Upper East Side resident, was rushed to Bellevue Hospital, where he succumbed to his injuries.

All drivers stayed at the scene and no arrests were made, cops said.

Students at a nearby school, I.S. 318, witnessed “the fallout from this tragedy,” according to City Council Member Lincoln Restler, who represents the area. 

In a post on X, he said he requested that the city’s Department of Transportation “perform an immediate review of safety improvements” at the intersection and that a crossing guard or traffic enforcement agent be assigned. 

“We know what it takes to design safer streets — but these serious crashes will keep happening if we do not act now to pass policies and implement redesigns to make our community safer,” he wrote.

“Every life lost to traffic violence is a policy failure.”