One day after a video surfaced of a pit bull attacking a woman in a New York City subway car, the head of the MTA on Wednesday asked straphangers to report animals that are improperly brought onto trains.

"There's no reason in the world why that dog was allowed, one, on board down to the platform, on the train, but let alone harassing one of my passengers," MTA Chairman Joe Lhota said. "I know the NYPD has focused on that now, I also know that our employees are aware of what the rules are. I'm as outraged as anyone when I saw that."

The person who posted the video said the attack happened last Friday on a number 4 train.

The dog can be seen biting a woman's shoe and tugging on her foot as the owner tries to pull the dog off.

Witnesses said the woman had asked the man to move his dog after it bumped her on her seat, and that she repeatedly pushed the dog off the seat before the man hit her. They said the woman hit the man back, and that's when the dog attacked.

MTA policy states non-service animals must be kept inside containers on subways.

Lhota said the owner of the pit bull should be prosecuted.

The NYPD said it is aware of the video and is investigating. Police are looking for the dog's owner.

Image above courtesy TahSyi Kyng via Instagram.