Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

New York's mass transit authority said it is investigating an incident involving a bus driver who a passenger alleges spit in her face following a dispute over a stroller.

"The bus operator depicted in this disturbing video is being held out of service while we conduct an investigation and we encourage anyone with information to contact us," Shams Tarek, a spokesman for the Metropolitan Transportation Authority, said in a statement.

A video posted on social media over the weekend appears to show a woman pushing a stroller near a bus stop in New York City. A bus driver can be seen running off a stopped bus and approaching the woman before he returns to the bus.

NBC News does not know what happened before or after the video or who may have instigated the dispute.

The woman, Sapphire Philip, 31, said in an interview Tuesday that the incident occurred Saturday evening. Philip was first identified by WABC-TV of New York.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Download the NBC News app for breaking news

She said Tuesday that she had bought a new stroller for her 2-year-old daughter while she was out shopping with both of her children in Brooklyn.

Philip said she told the bus driver as she was getting on the bus that she did not know how to close the stroller. She said she and the driver had a testy exchange.

"I just got off the bus," she said Tuesday.

Describing the incident shown in the video, Philip said the driver followed her off the bus, ran up to her and spit in her face before returning to the bus.

A spokesman for Transit Workers Union Local 100, which represents MTA bus drivers, said it was aware of the allegations and was speaking with the driver.

The spokesman, James Gannon, said the union has to wait and see what, if anything, the MTA is going to charge the bus driver with.

"When and if he is brought up on disciplinary charges, we'll defend him to the best of our ability," Gannon said.

The union did not provide the driver's name, and NBC News was unable to make contact with him.