PALMETTO BAY, Fla. -- Carbon monoxide fears forced firefighters to evacuate a Palmetto Bay apartment building after a fire was extinguished Monday night.

About 200 residents were displaced after flames ripped through the complex located at Southwest 88th Avenue and 146th Street.

When fire crews arrived, heavy smoke could be seen coming from the rooftop. It is believed the blaze started in one unit and spread to several others. As a result, power was cut off to several of the buildings as a precaution.

With no firewall, the dangerous gas carbon monoxide quickly built up. Normal levels are 30 parts per million, but officials said that on Monday night, the carbon monoxide level exceeded 500 ppm, which could be lethal. Firefighters said they had no choice but to break the doors down to make sure all the residents were out safely.

Evacuated resident Dalia Zayas said she heard the fire alarm but did not think much of it.

"An hour later, I'm saying to myself, 'Why haven't they turned off the alarm?' When I look out the balcony, I see the smoke," Zayas said.

Residents were not allowed back into their homes.

“They said if they would have let us fall asleep, we would have a bad headache or we would not have woken up. So, of course, I’m grateful," resident Shiniqua Wilkins told Local 10.

While no injuries were reported, one person did complain of having shortness of breath.

Windows and doors were opened at the complex in an effort to clear out the carbon monoxide.

The cause of the fire is still under investigation.

"Thank God nobody got hurt. It's just unfortunate, though," Wilkins said.

Residents whose apartments were not damaged are expected to be allowed to return home in the next couple of days. Fire officials said the carbon monoxide levels are safe again, and the doors that firefighters knocked down must be replaced.

The people who live in the six or seven units that were damaged might not be able to return for months, officials said. All other residents should be able to return home within the next couple of days.

Most of the displaced residents stayed with family members Tuesday night, although the American Red Cross put a few families into hotel rooms.