Jiu jitsu instructor Raz Chan and his students were on their way to lunch on Monday when they heard a woman screaming outside their studio.

It was coming from a car that was stopped at a red light in a southbound lane of Main Street at Broadway. The driver was being attacked.

“It was a pretty frightening, bloodcurdling scream,” Chan said. "Nobody was doing anything so we rushed over there."

Chan paused momentarily to assess the situation, wary that the attacker could have a weapon. He had little choice but to proceed, however; his student Matthew McKay was already charging toward the vehicle.

“Whether it was the safest reaction or not, I don’t know, but I had an instinctual reaction to run over,” McKay said.

Together, Chan, McKay and his other student Roniel Dio managed to grab the assailant, who was inside the woman's car, pull him onto the street and restrain him until police arrived.

“Certainly they’re heroes,” Vancouver Police Sgt. Randy Fincham said of the men from Gracie Barra jiu jitsu studio.

“They did what they thought was right and they stepped in to help this lady out,” Fincham said. “It was fortunate to have the right people there at the right time.”

Dustin Edward MacDonald, 24, was charged with attempted robbery and assault causing bodily harm. Police allege he jumped through the car’s open passenger-side window and tried to grab the keys from the ignition while fighting with the driver. Police believe he was trying to steal the car.

Paramedics treated the 41-year-old victim, whose name has not been released, for a minor bite on her arm. She was given oxygen at the scene of the incident and released.

The woman was “extremely shaken up” by the situation, Fincham said.

“I’m sure if you were sitting at a stoplight and someone dove in your car window and started biting you, even if you’re the toughest guy in the world, that’s probably going to be a scary thing,” McKay said.

MacDonald was scheduled to appear in court on Tuesday morning. Fincham said MacDonald, a Burnaby resident, is new to Metro Vancouver, but is already known to police here.

Fincham said it’s great to see bystanders helping out in dangerous situations, but that they should always do so with caution.

“If you are going to step into something like this, be aware of your limitations,” he said. “Don’t put yourself in a situation where you could get hurt.”

As far as Chan and his students are concerned, there was only one option in this situation.

“We just did what anybody would do,” Chan said. “Right? That could be your sister, your mother.”