Winnipeg police have released photographs of a man they say knocked the teeth out of a passenger on a bus after she tried to prevent another man from sexually harassing another woman.

Aisha Walker said she was on the Number 11 bus on Nov. 4 when a man started sexually harassing a female passenger.

Eventually, Walker stood up and put herself between the man and the woman he was harassing. Walker and the man got into a verbal argument.

"It kind of got heated, like, I was swearing. I was throwing insults, because he was, you know, being stupid."

That's when another man on the bus got upset and started arguing with Walker. The man punched Walker in the face before getting off the bus near Balmoral Street and Portage Avenue.

The blow shattered seven of Walker's teeth and left her with a black eye.

Aisha Walker says a man punched her after she intervened to help a woman who was being harassed on a Winnipeg Transit bus. (Aisha Walker)

Const. Rob Carver said Monday that police released the photos of the man they believe punched Walker because they hope the public will identify him.

"Our investigators have not been able to successfully identify those images at this point."

This particular situation was unusual, Carver said.

The punch left Walker with seven broken teeth, exposed nerves, a black eye and a bruise on her chest. (Aisha Walker)

"It's really strange. We've got two people arguing on a bus and getting confrontational. This person comes forward and attempts to, from what we understand, calm the situation. Out of nowhere, a [fourth] uninvolved person … goes up, and without provocation, assaults this person, who's really trying to do a good deed, you know, calm things down a little.

"I get it if someone gets involved in a confrontational situation and one of the people who is being confrontational directs that anger at the intervener," he said. "We see that. Tempers are flared, adrenaline's flowing, and we train our officers, it's always dangerous to intervene in an ongoing fight.

"This is very different, where someone who is not connected at all, without provocation, assaults this individual. This one's rare for sure, and concerning."

Police described the man as in his late 20s to early 30s, with a dark goatee, about six feet tall with a skinny build. He was wearing a brown or orange tuque, green parka, blue jeans and work boots.