Early Wednesday morning, an alleged gas line issue caused an explosion at the Highland Hills apartment complex. The blast and subsequent fire caused parts of the southeast Dallas apartment complex to cave in, injuring civilians and responders. Dallas Fire-Rescue reports that they dispatched crews to 5700 Highland Hills Drive at 10:20 a.m after reports of gas aroma inside the building. Residents of the apartment block were evacuated and are currently displaced from their homes.

Jason Evans, Dallas Fire-Rescue Spokesman, said that both apartment residents and first responders smelled gas “before the explosion occurred.” Firefighters were sent into the complex, and then around 10:30 a.m, the side of the building blew open. Photos acquired by NBC5 show a devastating scene of damage outside the complex. Windows were shattered, and fragments were “thrown 20 to 30 yards” out of the building. The explosion caused a fire that destroyed the structure, leaving charred and collapsed remains.

Evans says the fire was brought to a stop late on Wednesday, and the building was demolished due to safety concerns. Three firefighters were rushed to Parkland Memorial Hospital in critical condition, and a fourth was released with minor injuries. Four civilians were also taken to receive medical care, but as of 9 p.m Wednesday, all were cleared and released from the hospital in healthy condition.

Dallas Fire Chief Dominique Arts stated that the firefighters are expected to survive and recover and that officials are able to converse with each hospitalized firefighter.

Mayor Eric Johnson sent a message on Twitter after visiting the complex. Johnson wrote, “Please pray for our firefighters and for the civilians who have been injured.”

Atmos Energy, the company responsible for operating gas systems in Highland Hills, says that all gas lines were unaffected. In a statement, the company said, “Atmos Energy has verified that our system is operating as expected, and we have found no indication that our system was involved.”