Fort Worth – The Fort Worth Fire Department is responding to a gas explosion at the Houston St. Sandman Hotel Monday afternoon.

The first call came in at 3:32 p.m., FFWD said, and was followed by several calls of an “explosive type.”

According to MedStar, there are 11 patients. One patient is reported to be critically injured and two are critically injured. All patients have minor injuries. Nine patients were transported to local hospitals.

Craig Trojacek, public information officer for the FFWD, said through their investigation, “It appears to be some sort of gas leak;” However, he added that they were not sure whether the smell of gas was caused by explosion or fire or caused the explosion.

Fort Worth police said a family reunification area is being set up at 420 Main Street, Sundance Square.

All Tarrant County offices downtown are now closed.

Jason Allen spoke to someone who was in the hotel at the time of the explosion. He didn't want to look on camera, but said he smelled natural gas before the explosion, and he said to one of his crew, 'Do you smell natural gas?'

He said the smell was not strong, but they could smell it. He said the smell came from underneath them.

By then, the entire second floor was filled with dust and smoke. They could see the red EXIT sign and found the stairs. He told CBS News Texas that when he and his companions got to the stairwell, most of it was missing, so they were able to jump five or six feet down and get out of the building.

Jason Allen said natural gas still smells in the area. Trojacek said crews will continue to search the building to make sure everyone is evacuated.

At 5:30 p.m., the city of Fort Worth announced the “all clear” that “the hotel building has been destroyed and a missing hotel guest has been located.”

This is a growing story.