Instagram video shows dog attacking woman on NYC subway

Police are investigating a video of a pit bull attacking a woman on a Manhattan 4 train.
The incident happened last week and was posted to Instagram.
Witnesses onboard the train say the woman asked the owner to move his dog when it bumped her seat.
Onlookers say the woman pushed the dog several times until the man struck the woman.
Witnesses say the dog bit the woman’s shoe and would not let go after she hit the owner.
The MTA rules note that non-service animals need to be in carriers while on mass transit