The apartment fire that killed two men in Bozeman early Tuesday morning started on or near a couch on the first-floor porch, the Bozeman Fire Department said Thursday.

Several dozen firefighters responded to the blaze in a four-unit apartment building around 12:57 a.m. on March 1 at 215 S. 18th Ave.

Firefighters found childhood friends Dale C. Beard, 29, and Jacob P. Neuman, 30, both originally from Wyoming, in a bedroom in a third-floor apartment. The cause of the two men's deaths is still being determined, Gallatin County Sheriff and Coroner Jim Cashell said Thursday.

Four other tenants, including a 5-month-old infant, escaped without injury from the side of the building where the flames were fiercest. But they lost essentially all their belongings, including their vehicles.

Five men who lived in an apartment on the other side of the three-story building were also displaced.

Witnesses said the flames shot up the outdoor wooden stairway from the front porch in a matter of minutes.

The cause of the fire could not be definitively determined, but the fire investigation suggested that it was possibly caused by a cigarette.

Current building codes do not require outside stairways to be "fire-rated," Bozeman building official Bob Risk said. Indoor stairways must be shielded with sheetrock.

Built in 1983, the apartment building was also in compliance with codes that, at the time of construction, required apartment buildings only have one, centrally located smoke detector.

Multi-unit buildings constructed after 1991 are required to have alarms in each sleeping area, Risk said. And it is up to tenants to maintain the alarms.

In the third-floor apartment where Beard and Neuman died, firefighters found a wall mount for a smoke detector, but no unit attached to it.

Jodi Hausen can be reached at jhausen@dailychronicle.com or 582-2630. Read her blog at jhausen.wordpress.com or follow her on Twitter @bozemancrime. Reporter Amanda Ricker contributed to this report.