Police closed off part of the ground floor of Metrotown Shopping Centre after an apparent stabbing there just before 5 p.m. Saturday.

Burnaby RCMP said two groups -- both known to police -- were involved in the incident. They have one man in custody. Another was transported to hospital with non-life-threatening injuries.

Shoppers in the mall at the time posted photos of the scene -- including a trail of blood on the floor -- on Twitter, but officials inside were not particularly forthcoming about what had happened.

“They just said that there was a police incident and they didn’t disclose to us what had happened,” said Shauna Mathieson, who was in the mall at the time of the incident.

Mathieson said she checked the Internet to figure out what had happened, and she and Kevin Yip decided to leave.

“Nobody’s really telling you anything and you think maybe the person might still be there,” Yip said. “So we kind of decided basically with it all being quarantined off that there was just too many people. Everyone was just all over the place, so we figured it was best to just leave.”

The pair said the scene inside the mall after the stabbing wasn’t chaotic -- people were mostly curious what was going on behind the police tape -- but it was somewhat unnerving.

“I guess it kind of hits close to home,” Yip said. “You don’t really think that it can happen anywhere that you are, but when it does you kind of get a little bit worried, I guess. Scared.”

“Yeah, it’s definitely scary,” Mathieson said.