The fire department said it was the presence of multiple smoke alarms on each level of the home that awakened the students when the fire started at about 3:50 a.m., giving them enough time to escape.

"It was a potential disaster," said Jim Waycik, chief fire prevention officer for St. Catharines fire services.

He said the landlord in the home, located at 37 Cumming St., installed hard-wired smoke alarms in the basement, ground floor and upper level.

There were also traces of battery-operated detectors, bringing the number of total working alarms to five or six.

"She checked them regularly," Waycik said. "She was just devastated when she saw the fire."

The home has two bedrooms on the ground floor and four upstairs, three of which were occupied. It is suspected the fire originated with a candle in one of the ground-floor rooms.

Waycik said the tenant in the room tried to extinguish the fire, and another ran to the kitchen to retrieve a fire extinguisher, only to find the fire had grown too big.

"The kids tried to put the fire out initially, but it grew so quickly they all went out," he said.

One student living on the second floor opened his bedroom door and, seeing smoke, quickly closed it and climbed out his window which led to a roof. He jumped the short distance from the roof to the bushes, cutting his foot on the eavestrough.

His were the only injuries. The students have been taken in by the landlord until alternate living arrangements can be made.

Waycik said though the fire was under control fairly quickly, it swiftly spread upwards and destroyed the home.

"It went straight up the stairs," he said, adding that only in one room where the door was closed is there any salvageable property.

It's likely the structure was damaged so severely that the home will have to be razed, he said.

He said this fire reinforces the need for smoke alarms, which he credits with saving the students' lives. As well, he said, the blaze points to the need for alternate exits from every room in the house.

He said the location of the fire's origin would have prevented anyone from getting out of the basement living quarters.

Clutter can also compromise fire safety, he said.

"Clutter is a place for a fire to start and for it to burn, and it also restricts your exit," he said.

In this case, though, he said, the landlord stopped by the house weekly to ensure that the house wasn't too messy.

Waycik said the department is planning a new initiative for students and parents starting in January, when they will be holding presentations about what to look for in student accommodations.