The BC Wildfire Service said it's investigating a large brush fire that broke out near Squamish Monday and sent a thick plume of smoke into the air that could be seen from the Lower Mainland.

Footage from CTV's Chopper 9 showed the blaze burning roughly 17 kilometres up the Squamish valley.

As of 8 p.m., the fire was approximately 3.5 hectares in size, according to the fire information officer for the Coast Fire Centre.

Donna McPherson told CTV News Vancouver Monday night that the blaze is suspected to have started as the result of a homeowner doing open burns, adding that no structures were at risk.

One helicopter could be seen dropping water on the fire and there were firefighters on the ground battling the blaze.

McPherson said the six people and a helicopter were at the scene Monday night, and that an additional 20-person crew would show up in the morning, even though the fire is expected to "reduce significantly overnight" as the weather cools.

"The crews are on site. They're reporting what's called a moderate intensity ground fire," she said. "It's on very steep slopes in dry light fuels, on rocky ground."

An investigation into the exact cause of the fire is underway.