The U.S. Bureau of Alcohol, Tobacco and Firearms deployed its national response team to investigate a fire that consumed an under construction apartment building in Denver on Friday night.

The deployment of the team, which assists local officials in investigating major fires, explosions and bombings, is the fifth activation of the team this fiscal year, the agency said on social media Tuesday.

“(They’re) going to help draw this fire to a conclusion and give us some answers,” said Denver Fire Division Chief of Operations Robert Murphy said at a Tuesday news conference, noting the plethora of explosive, chemical and fire experts the agency will use to assist local authorities with the investigation.

Taking place at the intersection of Leetsdale Drive and South Forest Street in southeast Denver, the fire was first reported around 6:45 p.m. Friday and quickly burned through the building. The only reported injury so far has been a firefighter who threw out his shoulder after it got caught in a hose.

Murphy did not rule out any potential causes of the fire he described as the worst in his 30-year career with the department. He also noted the fact that the building was under construction at the time of the fire may have contributed to how quickly the blaze spread.

“It didn’t have full fire protection stuff in place, no fire alarms, no working sprinklers,” Murphy said. “The fire was able to run pretty cleanly for a while, and it just got to a point where it took over the rest of the building.”

Murphy added that investigators are still determining whether all construction-based fire prevention measures were being met when the building caught fire. Officials currently do not have a timeline as to when they will know exactly what happened.

As for the building itself, Murphy said that fire officials will talk to the ATF team Tuesday about when and how to topple the remaining structure and fully dissipate whatever hotspots may still remain under the rubble.

The ATF activated the same response team to investigate the fire that destroyed Nederland’s Caribou Village Shopping Center in October. As of Tuesday, the cause of that fire is still under investigation.

In total, more than 150 firefighters responded to the scene and about 18 million gallons of water were used from the beginning of the response until crews stopped spraying Monday.