(Bloomberg) -- An unmasked New York City police officer pushing a passenger out of a subway station won’t help the city’s struggling subways and transit system restore ridership and revive the economy, according to the acting head of the nation’s largest public transit provider.

A video of the Tuesday incident, which New York City Mayor Bill de Blasio said is under investigation, spread across social media, reinforcing an image of a dangerous transit system. In the video, one cop forcibly removed a male commuter after he asked the officer about not wearing a mask. He pushed the rider through an emergency exit door. The MTA requires riders to wear a mask or face a $50 fine.

The Metropolitan Transportation Authority, which oversees the city’s network of subway, buses and commuter rail lines, is struggling to bring riders back to its system. Its subways carry about half the weekday passengers it did in 2019 and ridership may not match pre-pandemic levels until 2024 or later, according to the MTA.

The incident comes as the MTA has worked to restore confidence in the transit system, with deep cleaning, mask mandates and additional police presence to combat an increase in crime on subways.

 “I’m upset by what I saw,” Janno Lieber, the MTA’s acting chief executive officer, told reporters Wednesday. “We count on our law enforcement officers to set an example. They gotta do it and frankly the city’s recovery is counting on people being able to be safe on mass transit.”

The ridership drop has decimated MTA’s finances, with federal coronavirus aid helping to cover lost revenue. The agency anticipates collecting $2.8 billion of farebox revenue this year, less than half the $6.4 billion total in 2019. “It’s going to be years before we work our way to 100%,” Lieber said at a MTA board meeting Wednesday about restoring ridership to 2019 levels.

MTA’s mask mandate applies to passenger and police officers, de Blasio told reporters Wednesday. He said cops not wearing masks is unacceptable.

“We’ve given this instruction 1,000 times and if you’re going to be in law enforcement, you actually have to participate in following the law,” the mayor said.

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