Smoke from a fire burning in a suburban Vancouver conservation area has blown across the highway, forcing roads to close and businesses to be evacuated.

The blaze in Burns Bog was first reported around 11:40 a.m. PT Sunday and gusting winds fuelled its growth throughout the afternoon, said Delta, B.C., fire chief Dan Copeland.

By evening, the B.C. Wildfire Service said the fire had grown to about half a square kilometre. Thick smoke could be seen billowing in the air and shrouding Highway 17, adjacent to the bog.

"We were struggling. We had heavy winds this afternoon," Copeland said. "They were a bit unpredictable. They were shifting on us and it was quite a dynamic fire."

One firefighter was hospitalized "due to a medical condition aggravated by the environment at the scene of the fire," the town of Delta said in an online statement

Provincial crews from other fire departments in the region were called in to help early Sunday afternoon. Altogether, there were more than 80 fire crews with air tankers and helicopters assisting.

Businesses evacuated

Smoke from the blaze eventually blew across Highway 17, forcing police to evacuate the Tilbury Industrial Area. That evacuation order was later scaled down, affecting only businesses on Progress Way between 76th and 80th Streets.

Delta police chief Neil Dubord said the evacuation was a precautionary measure.

"Certainly everyone is concerned about their businesses, but at this point in time, we don't feel that there's any threat to the businesses," he said.

Police also closed Highway 17 between Highway 99 and the Highway 91 Connector, diverting traffic around the fire, and the Fraser River was closed to marine traffic so air tankers could scoop water.

Dubord said it was unclear whether the roads would reopen in time for rush hour traffic Monday morning.

There was no indication Sunday evening of what caused the fire, Copeland said.

The fire chief described the blaze as a grass fire, and said embers from large deciduous trees are falling, creating spot fires.

"It's very dangerous," Copeland said. "It's very smoky."

The geography of Burns Bog also presents a challenge for fire crews.

Can burn out of sight

Located southeast of Vancouver, the 30-square-kilometre nature reserve is one of North America's largest peat bogs, and the fire can get under the dry peat where it will burn out of sight.

"If a fire gets underground in that peat, it can run a long way and pop up somewhere else. So it's a very major concern in that regard," said Delta Mayor Lois Jackson.

It's not the first time Jackson has witnessed a major fire in the area. She was mayor in 2005, when a blaze in Burns Bog grew to more than two square kilometres and took more than a week to put out.

The mayor said Sunday that she hasn't had time to think about the previous blaze.

"We're throwing everything we've got at this fire to get it out as soon as we can. Obviously, it's a very tricky fire to fight," Jackson said.

The mayor and emergency officials are expected to provide more information at a press conference Monday morning. 

With files from Jane Armstrong, Anita Bathe