A Manhattan man who hit and killed a pregnant traffic agent while driving his van Thursday afternoon has been charged with homicide, while the heroic efforts of strangers are being credited with saving the life of the woman's unborn child.

Police say 33-year-old Donnette Sanz was hit by a van driven by Walter Walker, 72, at East 188th Street and Webster Avenue in Fordham, Bronx.

Authorities say the impact sent Sanz, who was eight months pregnant, into the path of a school bus, which then slammed into her.

Witnesses say she was dragged and then pinned underneath.

"The van had hit the lady first, she flipped over. And the bus had got in the way, and hit her and ran her over," said eyewitness Timothy Ruiz.

Dozens of strangers rushed in to help the woman.

"So what we did, there was like 30 or 40 of us, we actually lifted that bus off of her, and pulled her from under the bus," said eyewitness Gary Burgess.

Sanz was taken to St. Barnabas Hospital, where an emergency cesarean section was performed. The newborn boy remains in critical condition in the hospital's neonatal section, but Sanz was pronounced dead before 4:30 p.m.

“It is a terrible poignancy that Donnette's son's birthday will now coincide with the day his mother died,” said Mayor Michael Bloomberg. “I hope that as this child grows up, he comes to understand that his mother gave her life in service to our city, and that we are forever grateful."

Walker was charged with criminally negligent homicide and unlicensed operation of a motor vehicle.