NEW YORK (CBSNewYork) — At least 15 people were injured in an extra-alarm fire in Washington Heights Monday.

The roof was going up in flames late Monday afternoon at the six-story, 133-unit brick building located at 775 Riverside Dr., between 156th and 157th streets, 1010 WINS Al Jones reported. The response level was ultimately raised to seven alarms.

The fire was believed to have started when a woman on the second floor tried to make toast with a toaster that had an electrical problem.

As CBS2’s Janelle Burrell reported, the FDNY was fighting the blaze from all angles Monday evening — even mounting themselves on buildings next door. But the building partially collapsed, and the smoky conditions made things more difficult.

“My daughter called me and told me the house was black and she couldn’t get out,” a resident said. “I told her, ‘Don’t open the door, call the Fire Department.’”

The first calls for help came in just before 2 p.m., with pockets of flames still flaring up from the roof for at least seven hours as firefighters tried to get a handle on the blaze.

“I opened the door and there was smoke. I came out with nothing on but a short-sleeve,” said resident Ruth Guzman. “It was horrible. Then we next door to 765 (Riverside Dr.) in the lobby. They had us go there.”

The stubborn flames went on ravaging the interior of the building for hours as firefighters worked to rip open the roof in their efforts to put it out, CBS2’s Valerie Castro reported.

The fire was finally brought under at 9:04 p.m. Emergency crews remained on the scene gathering their equipment as late as 11 p.m.

Fire officials said the fire began in a second-floor apartment. The fire spread into a dumbwaiter shaft that runs from the first floor to the top of the building and into the cockloft — the open area above the top floor and beneath the roof, according to Fire Commissioner Daniel Nigro.

“A cockloft is a wide open area that is very difficult for us to reach,” Nigro said. “We either have to cut through the roof or break through from the ceiling below. It’s very hard work under very arduous conditions.”

Samuel Devore was on his way home when he saw the smoke.

“Devastation because I couldn’t even get in,” he said. “I smelled the smoke all the way from Amsterdam (Avenue).”

As the fire raged, residents scrambled to escape. CBS2’s Burrell spoke with some of the people who evacuated.

“We watched it for a while. We were trying to figure out whether we needed to leave. Then it started going up the floors, then it was where there were firefighters inside, and it seemed like they had put it out – and then the fire started again from that window where it had started. Then windows started blowing out, and then firefighters started knocking out windows,” said resident Martha Ackelsberg.

Ackelsberg said she saw flames bursting onto the roof and decided it was time to go. Those who escaped were concerned about their neighbors late Monday.

“I’m concerned about the people who got injured and how they’re doing, because my neighbor who was in the apartment where it supposedly started at, she was taken to the hospital, so I don’t know her condition right now,” Devore said.

One man named Richard told WCBS 880’s Alex Silverman that the recent freezing weather had already made life in the building a nightmare.

“People have been complaining with no heat, using their ovens to try to heat their apartments, ceilings leaking, ceilings falling in on people – just, it’s been a lot to deal with, prior to this,” he said.

Some residents from the buildings next door were also evacuated as a precaution.

The injured included seven residents, four police officers and four firefighters, officials said. Nigro said he expects the number of injuries to go up.

Most of the injuries were minor, and none were life-threatening, officials said.

Following the fire, Our Lady of Esperanza Church acted as a Red Cross shelter, comforting residents with food and information. Many were just grateful to have survived.

“We all came out alive, and that’s very important,” Guzman said.

In the rush to get out of the building, some people also had to leave their pets behind. CBS2 has learned of at least one dog that was found alive by firefighters.