VANCOUVER -- Mounties are investigating after a bizarre incident in a Langley mall involving a male suspect with a long gun and an assault on a 15-year-old boy.

Video posted to social media shows the suspect wearing a large coat and jeans and walking near the H&M store inside Willowbrook Shopping Centre. He then pulls out what looks like a long gun, possibly a rifle, and begins running, leaving the frame of the shot.

Langley RCMP Sgt. Rebecca Parslow told CTV News Vancouver the incident occurred around 4:30 p.m. Tuesday afternoon and involved a dispute between two groups of young people who knew each other. The incident was not related to the ongoing Lower Mainland gang conflict, however, Parslow said.

She said the suspect struck a young person in the head with the butt of a firearm and fled the scene. The youth suffered minor injuries, but was not taken to hospital.

The RCMP investigation is ongoing, and no arrests have been made, Parslow said.

The owner of a nearby business told CTV News she heard loud yelling outside the Sport Chek store at the time of the incident. She said a nurse inside her store at the time ran out to help the injured teen.

Sabrina Gidon works at the mall and witnessed the altercation. She told CTV News she ran to help the boy after the incident occurred.

"I felt really bad for him," Gidon said. "He was obviously in a lot of shock, because he was shaking pretty violently and he had just been hit in the back of the head."

Gidon said the boy told her his age.

"It's mind-boggling," she said. "To hear that 15-year-olds are getting hit over the head or even guns pointed at their direction is just shocking. Just shocking. And sad."

Parslow said police are working to determine what started the dispute between the two groups, and are asking anyone who witnessed the incident or has information about it to call the Langley RCMP non-emergency line at 604-532-3200.