A woman was rushed to hospital after being attacked by a dog in South Vancouver on Friday.

The attack took place at 56th Avenue and Fraser Street, shortly before 4 p.m. The City of Vancouver confirmed a second person was also attacked, but was uninjured and walked away from the scene before officials arrived.

Few details have been provided so far, but a witness told CTV News that he was driving by when he saw a large brown dog cross in front of his car.

"This woman was walking and next thing you know, I see the dog going for her," the witness said.

"It wasn't on a leash, it was just by itself."

The dog ran up, jumped on the woman and bit her on the head, he said.

"As soon as I saw the dog attack I had to stop and I shouted at the dog, and that's what made the dog let her go," he said.

He got blood on his clothes as he helped the woman, who had a cut lip and injuries to the left side of her head and left thigh.

The dog took off as ambulances raced to the scene.

The witness asked two bystanders to keep an eye on the dog until Animal Control officials arrived.

"She was bleeding quite badly so I had to stay with her. I had to stop the bleeding," he said.

The attack is not the first incident involving an aggressive dog this week. On Monday, a Surrey woman was mauled by a pit bull that has since been surrendered to be put down. Later the same day, a Pomeranian puppy was injured in a pit bull attack.

Animal Control is currently investigating the incident.