The man was rushed to hospital by ambulance shortly afterwards. Police have yet to say what sort of injuries he suffered, or if he was shot by police or himself.
The Independent Investigations Office (IIO) was called in shortly afterward to handle the investigation of the incident.
The man's identity has not been released by police.
The incident began around 6 a.m. PT outside the Starlight Casino in New Westminster when police responded to calls about a man with a gun.
Police quickly shut down traffic in the area including the Queensborough Bridge throughout the rush hour on Thursday morning.
The incident also affected some bus routes in the area, but traffic and bus service was returning to normal by 11:30 a.m. PT.
Not a hostage taking
Around 7:30 a.m. PT CBC reporter Steve Lus said he could hear police on a loudspeaker apparently negotiating with someone at the casino.
"Put down the gun. We don't want anyone to get hurt. Put down the gun," police could be heard repeating on the loudspeaker.
At first the suspect was apparently refusing police requests to give him a cellphone to continue negotiations, but it appeared he later agreed to talk to police via cellphone, and at around 9:30 a.m. he could be seen sitting on the ground talking on a phone.
The Starlight Casino was locked down and people inside were told to remain inside during the incident.
New Westminster Police Insp. Phil Eastwood confirmed a woman was involved at the onset of the incident, but she was safe with police. He said the incident was not a hostage-taking.