Authorities say the driver of a Department of Sanitation sand spreader struck and killed a woman Tuesday morning before fleeing the scene.

Police say the driver was trying to make a left onto Willis Avenue from East 138th Street when he struck the pedestrian, who witnesses say was an older woman.

Maximo Diaz says he saw the incident around 6:36 a.m. He says he was driving two cars behind the sand spreader and saw the pedestrian being struck.

The NYPD Highway District's Collision Investigation Squad says the driver fled the scene. Diaz says he and the car in front of him almost hit the woman as well.

However, he used his car to stop traffic so the unidentified victim would not be hit again.

Police pronounced the victim dead at the scene. The medical examiner removed the body just before 10 a.m.

A DSNY spokesperson released a statement saying: “We are cooperating fully with the police investigation. Additionally, DSNY safety personnel are conducting an investigation as well.”

The DSNY says the driver has been suspended. Police have not yet announced any arrests.