NEW YORK >> A pregnant young woman who was feeling ill was headed to the hospital with her husband early today when the car they were riding in was hit, killing them both, but their baby boy was born prematurely and survived, authorities and a relative said.

The driver of a BMW slammed into the car carrying Nachman and Raizy Glauber, both 21, at an intersection in the Williamsburg neighborhood of Brooklyn, said Isaac Abraham, a neighbor of Raizy Glauber’s parents who lives two blocks from the scene of the crash.

Raizy Glauber was thrown from the car and her body landed under a parked tractor-trailer, said witnesses who came to the scene after the crash. Nachman Glauber was pinned in the car, and emergency workers had to cut off the roof to get him out, witnesses said.

Both of the Glaubers were pronounced dead at hospitals, police said, and both died of blunt-force trauma, the medical examiner said.

Their infant son was in serious condition, said Abraham. The hospital did not return calls about the child. The Glaubers’ driver was in stable condition, police said. Both the driver of the BMW and a passenger fled and were being sought, police said.

On Saturday, Raizy Glauber “was not feeling well, so they decided to go” to the hospital, said Sara Glauber, Nachman Glauber’s cousin. Abraham said the Glaubers called a car service because they didn’t own a car, which is common for New Yorkers.

The Glaubers were married about a year ago and had begun a life together in Williamsburg, where Raizy Glauber grew up in a prominent Orthodox Jewish rabbinical family, Sara Glauber said.

Raised north of New York City in Monsey, N.Y., and part of a family that founded a line of clothing for Orthodox Jews, Nachman Glauber was studying at a rabbinical college nearby, said his cousin.

Brooklyn is home to the largest community of ultra-orthodox Jews outside Israel, more than 250,000. The community has strict rules governing clothing, social customs and interaction with the outside world. Men wear dark clothing that includes a long coat and a fedora-type hat and often have long beards and ear locks.

Jewish law calls for burial of the dead as soon as possible, and hours after their deaths, the Glaubers were mourned at a funeral Sunday afternoon. Dozens gathered shoulder to shoulder on the street outside, men in hats and women in shawls or head coverings, nearly everyone in black. The sound of wailing filled the street as the two black-draped coffins were carried from a vehicle.

After the funeral began, a speaker sobbed uncontrollably, his voice choked with grief and echoing over loudspeakers set up outside.

Just before, Sara Glauber spoke admiringly of her cousin.

“You don’t meet anyone better than him,” she said. “He was always doing favors for everyone.”

She said Nachman’s mother herself just delivered a baby two weeks ago.

“I’ve never seen a mother-son relationship like this,” said Sara Glauber. “He called her every day to make sure everything was OK. He was the sweetest, most charming human being, always with a smile on his face.”

She added that, of him and his bride, “if one had to go, the other had to go too because they really were one soul.”