Four men who died in a residential trailer fire in Selkirk, Man., may not have been able to escape because both of the home's exits were blocked, a local fire official says.

RCMP and fire crews were called to Bermuda Bay in Selkirk just before 5 a.m. CT on Saturday, where they found the fire had quickly engulfed the trailer.

Selkirk fire Chief Dan Thorsteinson said the blaze started near the trailer's front door, but it took firefighters five minutes to get inside because the back door was blocked with household items.

The fact that both doors were blocked might explain why the four men did not get out in time, he said.

"They figure it's like a minute and a half to get out of the building," Thorsteinson told CBC News on Sunday.

"If you're sleeping, you got to shake your head, get your bearings and try and get to an exit. And if the fire's in one end, the secondary means of egress should be in the other end."

Thorsteinson said residents need to make sure they have two clear exits in their homes in case of fire.

"The fire and smoke travel fast. You normally die from smoke inhalation; you don't necessarily perish from the impact of the flames," he said. "If you can't see and you can't breathe, how much time have you got?"

'I just dropped'

Lawrence Traverse, 42, his son Gerald, 18, Jason Marsh, 39, and Aaron St. Jean, 37, died in Saturday's fire.

Lawrence's mother, Alvina Traverse, said news of her son's death has hit her hard.

"Oh, I just dropped, and I've had such pains in my chest ever since," she said.

The elder Traverse said Lawrence turned to alcohol in the years after his two-year-old daughter, Heaven Traverse, died in 2005.

Alvina Traverse said her family had been caring for Gerald for about six or seven years.

"We're going to miss him lots; he's just [one of] like our own," she said.

A fifth man who escaped the fire was transported to the Health Sciences Centre in Winnipeg in critical condition.

A spokesperson for the Winnipeg Regional Health Authority told CBC News the man was in the hospital's critical care unit on Sunday afternoon. Neighbours identified him as Brendan Crate, who they said was a visiting friend of the residents.

The cause of the fire is under investigation by Manitoba's fire commissioner.