Aug. 11 update: Regional authorities in Metro Vancouver have lifted an air quality advisory triggered by a massive barge fire on the Fraser River Friday.

Firefighters are attacking a massive blaze that broke out Friday morning on a barge loaded with crushed cars on the Fraser River.

Multiple explosions have been heard coming from the burning barge, which is moored at a steel recycling plant near the Pattullo Bridge on the Surrey side of the river.

It's unclear whether anyone has been injured.

Deputy chief John Lehmann of the Surrey Fire Service said the blaze initially posed a challenge for crews because it started near the middle of the 76-metre vessel.

"Three sides of it are surrounded by the water," Lehmann said. "Given that our crews could only access it from the ramp we were only able to get water onto the front portion of the barge."

A firefighting boat from Vancouver Fire and Rescue Services has since joined the effort and started dousing the barge from the river.

The blaze sent a huge plume of smoke into the air that could be seen from neighbouring cities and triggered an air quality advisory for Metro Vancouver shortly after noon.

Regional officials warn that high concentrations of fine particulate matter have been recorded sporadically since the fire broke out. 

"Persons with chronic underlying medical conditions should postpone strenuous exercise until the advisory is lifted. Exposure is particularly a concern for infants, the elderly and those who have diabetes, and lung or heart disease," Metro Vancouver said in a news release. 

Anyone who experiences symptoms such as chest discomfort, shortness of breath, coughing or wheezing is encouraged to check with a healhcare provider. 

Lehmann said the crushed cars likely contain plastics and upholsteries, and that’s what’s fueling the fire.

Firefighters expect to remain at the scene battling the flames all day and potentially through to Saturday.

The cause of the fire hasn't been determined.

With files from CTV Vancouver's Nafeesa Karim