An argument over a dog and a metro seat escalated until the dog bit the foot of the woman and wouldn’t let go.

It happened on Friday on a crowded No. 4 train on New York City's subway, WNBC reported.

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Eyewitnesses say a man brought the dog onto the train and had his animal sit in a seat, WABC reported. The dog bumped into the woman, who was not happy that an animal was sitting in the seats. Eyewitnesses say she asked the man to move his dog, but the man refused. Witnesses said she shoved the dog from the seats, and the owner had the dog jump back up. She shoved the dog again before witnesses said the man punched her. The two started fighting. Then, witnesses said, the dog bit the woman's foot, WABC reported.

People on the train screamed at the pair, "Get the dog off her," but the dog would not let go until she removed her shoe, WNBC reported.

The man and the dog left the train at Wall Street.

Witnesses said the woman appeared to be OK, WNBC reported.

The Metropolitan Transit Authority said that non-service animals should be in a carrier. The video has been given to the NYPD, the New York Post reported.