HARTFORD, Conn. (WTNH) — A second-alarm fire broke out at an apartment complex in Hartford early Thursday morning.

Hartford firefighters responded to the 16-unit apartment complex on Park Street, located in the city’s Frog Hollow neighborhood, just before 5 a.m. News 8 was first on the scene as firefighters were dousing the flames.

Firefighters requested a second alarm due to the size of the building and current weather conditions, Hartford Fire Chief Mario Oquendo Jr. said.

Fire officials said the fire started on the third floor and spread up the pipe chase to the fourth and fifth floors. Multiple apartments and electrical components were affected and officials determined the entire building is uninhabitable.

Oquendo Jr. said it’s unknown how many people are displaced. The American Red Cross is helping those affected.

No injuries were reported.

Fire marshals are investigating the cause of the fire.