AUGUSTA — All but one of the 15 people living at the State Street apartment building damaged beyond repair by a fire Friday night have found housing elsewhere in the area.

The state fire marshal’s office determined Saturday that the fire that destroyed the third floor was caused by a tenant in a second-floor apartment disposing of cigarettes in a plastic bag.

On Monday, APEX Management Company placed all residents of 15 State St. in vacant units in the Augusta area managed by the company with the exception of the woman who started the fire, said John Michaud, owner of the property management company. He said he expects all the tenants to sign leases at the locations.

The city determined Monday that the building should be torn down, and Michaud said his company plans to demolish it as soon as possible. He said he met with contractors Monday and expects progress to be made within a week.

An apartment building several feet away from 15 State St. will remain closed to residents until the damaged building is torn down, Code Enforcement Officer Robert Overton said. If the damaged building collapses, it will very likely hit the nearby building at 13 State St., he said.

“If it does fall, we are worried about the safety of the people in that other building,” Overton said.

Michaud, whose company also manages 13 State St., said there was only one person living in the two-unit apartment building. He said the tenant was out of town at the time of the fire, and he doesn’t yet know where she’ll stay if the other building isn’t torn down before she returns.

Neither of the city’s code enforcement officers, Overton and Gary Fuller, said they had ever inspected the two State Street apartment buildings. Fuller said the city doesn’t have any records of previous complaints at either building. The city had only been inspecting buildings if there were complaints, but it has been more proactive about its inspections in recent years because of a new ordinance governing apartment buildings with tenants receiving aid from the city, Fuller said.

The city approved the new ordinance in 2013 requiring landlords who rent to tenants who receive General Assistance housing money from the city to allow city workers to inspect the apartments and common areas of those buildings to ensure they meet safety codes. No residents at 15 State St. were receiving General Assistance funds from the city, according to Leif Dahlin, the city’s director of community services.

The American Red Cross had paid for the 15 displaced residents, including seven children, to stay at the Super 8 motel in Augusta. The organization also gave them funds to allow them to buy food and clothing and assisted with other immediate needs, including medications.

John Lamb, spokesman of the American Red Cross of Maine, said the organization has caseworkers meeting with the displaced individuals to determine any additional needs and help them begin to recover. He said the organization is still working with the city and area agencies to find housing for all residents.

Firefighting crews from several area fire departments responded to the fire reported at 7:20 p.m. Friday and didn’t clear the scene until around 2 a.m. Saturday.

Investigators with the Office of the State Fire Marshal, who were at the scene Friday night and Saturday, determined the fire started because a tenant in apartment No. 3 on the second floor was throwing cigarettes into a plastic bag, according to Battalion Chief Jason Farris of the Augusta Fire Department. The bag ignited and the fire spread to a carpet, a mattress and a bureau, he said. Farris said residents said they heard smoke detectors going off.

The fire destroyed the building’s third floor and heavily damaged the second floor. One resident was taken Friday night to MaineGeneral Medical Center with unknown injuries but was later released.

“To put cigarettes in a plastic bag on a carpet, that’s not a safe practice,” said Fire Chief Roger Audette, who pointed out that the fire that killed six people in Portland was also caused by discarded cigarette butts. In that case, there were no working smoke detectors to alert occupants of the fire.

Smoking was the most common cause of fatal residential building fires in 2012, at 15 percent, according to the U.S. Fire Administration.

The National Fire Protection Association reported that in 2011 there were 90,000 fires caused by cigarettes in the U.S., killing 540 people, injuring 1,640 civilians and causing $621 million in damage.

The neighborhood has been the scene of several fires over the past year, including two within days of each other in December. Those fires, at 20 State St. and 36 Northern Ave., left more than 30 people homeless. Last summer, there were two other fires in State Street apartment buildings within a few hundred feet of the site of Friday’s fire.

Paul Koenig — 621-5663

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Twitter: @paul_koenig