A desperate woman facing eviction from her south Santa Rosa apartment poured gasoline over her body Sunday evening, before setting a fire that nearly destroyed the four-unit property and cost herself and three families their homes, a Central Fire official said Monday.

“She was very desperate and she basically doused herself and her bedroom and her mattress in gasoline. She laid down, lighter in hand, and flicked the lighter,” said Cyndi Foreman, a fire prevention specialist with the Central Fire Authority of Sonoma County who led the investigation.

“The room erupted in flames. She tried to escape out of her bedroom window. Her son … burst in and dragged her out and saved her life,” said Foreman. “Fortunately, no one else was hurt.”

Melissa McMullin, 44, was hospitalized Monday at Santa Rosa Memorial Hospital with third-degree burns on parts of her body. While she is suspected of arson, she hasn’t been arrested. Fire investigators, Sonoma County sheriff’s detectives and mental health officials were working on the case.

Her son, Robert McMullin, was treated for smoke inhalation but was otherwise unhurt, said Foreman.

Fire officials Monday estimated damage to the Barbara Drive property to be as much as $500,000 because of the extensive damage to the building and belongings in the four apartments. Two apartments were gutted, and two had major fire and smoke damage.

The Red Cross is helping the 12 or so displaced residents with three nights of housing. On Monday morning, several returned to the property to see what they could salvage.

“It’s a shock. Most everything is completely destroyed,” said Charletta Colón, whose home was destroyed. She had lived there for the past six years or so with her mother, stepfather and sister.

Lost to the fire were the day-to-day household items, but more painful were sentimental things like her great-grandmother’s teapots and some old family jewelry, said Colón. “I found a photo album. I’m grateful for even that.”

The fourplex on Barbara Drive, near Moorland and Hearn avenues, is owned by David Chang of Santa Rosa. It was built in the late 1960s, said Foreman. Chang could not be reached for comment Monday.

Foreman said she was told that McMullin, who also used the name Melissa Terry, was due to be evicted April 30 because of ongoing disputes with neighbors.

Investigators spoke to McMullin on Sunday night and Monday morning, hearing the woman’s confession. McMullin told investigators she had texted her sons a goodbye note and had intended to kill herself, said Foreman.

The woman lived in one of the middle apartments in the U-shaped fourplex. Her neighbors included one of her sons and extended members of Colón’s family and at least two young children.

“We were like a big family here,” said Colón. “It’s really shocking she would do something like this.”

The fire was fueled not only by the gasoline — a gas can was found Monday morning in the charred remains of the woman’s bedroom — but also as many as eight oxygen cylinders that exploded during the fire. McMullin had used oxygen for a health issue, Foreman said.

She suffered third-degree burns on her lower arms and her feet, escaping other injuries despite having soaked herself with gas. While the vapors in the room caught fire, it was the heavy soaking of her clothes that saved her — they were too wet to spark, Foreman said.

Colón, who knew the neighbor as “Melissa,” said the woman had a reputation for “tantrums. Cussing, yelling and screaming.”

Colón had been about to head to work Sunday evening when she heard glass breaking and thought the woman had thrown something. But she said she then smelled smoke and spotted the fire. Things then moved quickly.

“Her son came running around the other side of the house out of nowhere like a superhero,” said Colón.

When he found his mother’s door locked, he busted a window and jumped through, then unlocked the door, allowing Colón’s boyfriend to dash in.

The boyfriend then came back out, seeking a hose and telling Colón the burning woman was attempting to crawl off her bed.

As the son was trying to get her outside, an explosion startled them and the woman fell face first to the ground. He helped her up and pulled her away, said Foreman.

“We could hear more explosions. Within seconds it just took over. The place was just done,” said Colón. “We’re in shock still. Trying to help each other figure out what to do next.”

Foreman said that with the gasoline and oxygen tanks, the fire’s devastation could have been far worse.

“An enormous dollar amount was saved here as well, keeping this to just this fourplex,” she said. “Homes are tucked in here tight.”

You can reach Staff Writer Randi Rossmann at 521-5412 or randi.rossmann@pressdemocrat.com. On Twitter@rossmannreport.