Video: Mass Explosion at Historic Texas Hotel Injures 21 People, Traps Guests in Basement The cause of the explosion is currently under investigation.

An explosion at a hotel in Fort Worth, Texas, on Monday afternoon left 21 people injured, according to authorities.

Around 3:30 p.m., firefighters responded to multiple calls about an explosion and a fire at the Sandman Signature Fort Worth Downtown Hotel.

A spokesperson for the Fort Worth Fire Department, Craig Trojacek, told NBC News that the area smelled of gas and that the explosion is believed to have been caused by a "gas leak," though it is unconfirmed what exactly prompted the explosion.

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One victim is in critical condition, and four others had serious injuries.

First responders continued a canine-led search and rescue operation Tuesday morning and noted that no additional victims had been located.

Photos of rubble and the scope of the devastation flooded social media.

BREAKING: Moment captured after major gas explosion at Sandman Hotel in Fort Worth, Texaspic.twitter.com/LBXwI6tCOM

— Insider Paper (@TheInsiderPaper) January 8, 2024

Explosion in downtown Fort Worth, TX at the Sandman Hotel

According to Medstar, at least 11 people are injured. @FOX4 pic.twitter.com/8V1SHhZrgz

— Peyton Yager (@peytonyager) January 8, 2024

"There was debris. There was insulation. There was office furniture," witness Charlie Collier told The Associated Press. "Everything that was in the first couple floors of the building was blown out all over the street."

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Authorities said that several victims were trapped in the basement of the 20-story hotel and there were two dozen rooms booked at the time of the explosion.

"Emergency responders are on site, and we are working closely with the authorities to understand the origin of the event and the extent of the harm caused," The Sandman posted on its website. "The safety and well-being of our team members and guests is our priority. We are working with those who have been injured to fully support them at this time."

The cause of the explosion is under federal investigation.