Officials say 13 people suffered from smoke inhalation after a fire erupted at an apartment complex in Hartford.

It happened Saturday around 10 p.m. on Evergreen Avenue.

A passerby saw the fire and knocked on the door of a nearby fire house which was coincidentally running a fire exercise.

All residents were evacuated – 13 of which were taken to the hospital.

Hartford Fire Department Chief Rodney Barco said the fire posed challenges for responding crews.

"Limited visibility, heavy smoke conditions, and just trying to find out exactly where this fire was located. So all of those challenges presented itself to the men and women of our fire department, but they did an excellent job mitigating the situation," said Hartford Fire Department Chief Rodney Barco.

Crews are investigating what may have sparked the fire.