A "staffie-like" dog has injured a "small, black dog" on the Esplanade in an incident witnesses describe as "horrific" and "vicious".

South Wales Police have confirmed that the incident took place at 4.30pm and that the smaller dog was taken to the vets.

A witness says both dogs were on their leads and that the ordeal lasted "at least three minutes".

"The larger dog just went for it and wasn't letting go - just shaking it around," she tells Nub News. "The guy who owned [the attacking dog] was in total shock, screaming and yelling at his dog to try to get it to stop. But it had just clamped down."

She said passersby rushed to rescue the small dog, who was being walked by "two women and a young child."

"The child was in hysterics. People were rushing over, bringing brooms to try to get the dog off. It must have lasted at least three minutes but it felt more like 15. I'm still shaking.

"Someone came with a big blanket and they rushed the dog to the vets. I'm assuming the dog was still alive at this point.

"The guy then went to sit far away with his dog and was in obvious shock. The dog must have just thought it was attacking a rodent or something.

"I feel so sorry for him because it somehow seemed like a one-off. The dog actually looked very friendly."

The condition of the dog is currently unknown.

More to follow.