A blast that echoed through downtown and across the Assiniboine River was caused by two tires exploding after a commercial truck caught fire.

Firefighters quickly put out the blaze at Donald Street and Hargrave Place, which happened at about 12:20 p.m. Monday, said a spokesperson for the city of Winnipeg. No one was hurt.

A nearby building was ventilated but not evacuated, said a firefighter on the scene.

Truck owner Patrick Tench said he believes a hose on the truck gave out, sparking a fire.

"We think there was a hydraulic line failure … it hit something hot, flashed, the outside of the truck caught fire," he said Monday while looking over his plumbing truck.

The fire spread to two tires, which caused the loud boom that reverberated through the area and was heard across the river when they exploded.

Tench said the tires "just smoked up, because you're burning rubber."

Smoke billows from a truck fire on Hargrave Place downtown Monday. (Jackie Coleman/Submitted)

Jackie Coleman was in her apartment in Osborne Village when she heard "a loud bang."

She ran to the window to see thick black smoke billowing up from across the river, around an "apartment building I knew was on Hargrave.

"It kept just kind of coming up around the building, and there was a lot of sirens."

The smoke soon turned white and petered out, she said, adding while she wasn't concerned for her safety, she was worried someone had been hurt.

Firefighters had to cut open a pipe on the truck to stop the fire's spread. (Tyson Koschik/CBC)

Despite the tires catching fire, damage was minimal to the truck and the building, said Tench, although one tire hit a building window.

The truck was only carrying potable water and was draining a sump pit after the weekend's heavy rains, said Tench.

"That's all we were taking. Water out of a sump pit. Just an old hose decided to let go at the wrong time. I just had it in for a safety too.

"Just one of those things."