The blaze was first spotted at about 2:55 p.m. Thursday by Ian Myers, who was walking home down nearby Height Street from a grocery store.

“I just noticed all the smoke from the side of the house,” he said, adding he at first believed someone was having a backyard bonfire.

When he walked towards the home at 4 Disher St., Myers said he saw flames shooting from the back of the house.

“It looked like the whole house was on fire,” he said.

He used his cell phone to call 9-1-1 and looked to see if anyone was home.

Wilf Demore, a neighbour across the street, said the home belongs to a couple and their two teenaged sons. He said he was in the back of his house with his grandchildren and didn’t notice anything was going on until the fire trucks arrived.

Myers said he didn’t believe anyone was home until he saw the couple’s 13-year-old walk out the front door.

St. Catharines fire chief Mark Mehlenbacher said the boy was not injured in the blaze.

“He said he was fine, didn’t take in any smoke,” Mehlenbacher said, adding the boy was checked over just to be sure.

Smoke could be seen billowing out the front top window and from underneath the roof shingles. Firefighters were on the roof, cutting into it with a saw in order to gain access to it and allow the smoke to ventilate out.

Mehlenbacher said it’s unknown at this time how the fire started.