Firefighters are working to figure out what caused a fire that broke out inside a Homecrest apartment building Monday evening.

The fire happened at a six-story building on East 13th Street just after 5:30 p.m.

According to fire officials, the flames started on the second floor. Crews responded quickly and were able to get the fire under control in less than an hour.

Officials say two people were taken to the hospital. One person is in critical condition, while the other has injuries that are not considered life-threatening.

As a result of the fire, a partial vacate order is now in place for the building. That means some residents may not be able to return to their apartments right away because of safety concerns.

Video from the scene shows emergency crews taking a person out of the building while neighbors watched from outside. Other footage shows the aftermath, with residents gathering on the street after being forced out.

Tenants say the moments inside were chaotic and scary as smoke quickly filled the building.

“After dropping off my son, I came back and smelled smoke,” said Kristina, a tenant in the building. “I had to run out to the fire escape because I couldn’t go down the stairs. It was terrifying.”

The American Red Cross says it is helping three households, made up of six adults, with emergency assistance, including temporary housing.

The cause of the fire is still under investigation.