Firefighters are on the scene of a large apartment fire in the Castleton area.

INDIANAPOLIS (WTHR) — Firefighters are on the scene of a large apartment fire in the Castleton area.

The fire broke out around 1:30 a.m. Thursday on Whipporwill Drive in the Waterside at Castleton Apartments.

Video posted by a witness on Twitter shows at least one apartment building fully engulfed in flames.

Three firefighters suffered slight injuries. Two went to the hospital for treatment for dehydration. Medics on the scene treated the third for a cut. There were no other injuries reported.

IFD credited the working smoke alarms for ensuring all residents safely evacuated.

New information: 2 firefighters hurt from the heat fighting Castleton fire. Believed to have minor injuries. No residents hurt. #WTHRSunrise

— Matt McCutcheon (@matt_mccutcheon) May 3, 2018

The flames were so large dispatchers received multiple calls from drivers on Interstate 69 about the fire.

Neighbors in the building next to the burning one say the heard and felt the fire, then went to warn residents in that building to get out.

Firefighters say neighbors in the building to the left rushed to the burning building on the right pounding on doors to get people out; credited with no Waterside at Castleton residents getting hurt. 2 firefighters have minor injuries. #WTHRSunrise

— Matt McCutcheon (@matt_mccutcheon) May 3, 2018

"We were trying to get people to come outside, and trying to get people's attention," said Justice Runion, who lives on the first floor of the building. "So we got in our cars — somebody was calling 911 obviously — and trying to honk to get people's attention so they would look outside. And when they did, we were trying to wave them out, 'There's a fire! There's a fire!'"

An IFD official said the fire damaged 16 units and displaced at least four families.

It's unclear if all the affected residents have rental insurance to help rebuild their lives.