FORT WORTH, Texas (NEXSTAR) — An explosion at a Texas hotel in Fort Worth on Monday littered downtown streets with large section of building and debris and injured multiple people, authorities said.

Investigators believe the blast was caused by natural gas, said Bureau of Alcohol, Tobacco, Firearms and Explosives spokesperson Sara Abel, who was briefed by local police.

Aerial footage in Fort Worth, Texas, showed debris from the hotel scattered across downtown streets as authorities said they were responding to a “major incident” and urged people to avoid the area. The Sandman Signature hotel is in a busy area of downtown about one block from the Fort Worth Convention Center.

Fort Worth City Councilman Carlos Flores posted on Facebook that there had been a gas leak and an explosion. “Several streets closed,” Flores wrote. “Please avoid this area.”

The city’s emergency medical service has sent nine ambulances to the scene and found “multiple” people injured, although a spokesperson could not immediately say how many. Desiree Partain of MedStar said there are not any fatalities reported so far but stressed that they were still assessing the situation.

Partain said she could not characterize the types of injuries that medical staff were finding and said she did not know their cause.

“My heart and prayers are with those who were injured as we continue managing response,” Fort Worth Mayor Mattie Parker said in a statement, adding that she would provide more information once it was available.

Fort Worth Fire Dept. officials have set up a family reunification area in Sundance Square in Fort Worth for family members of those who may have been involved in the incident, according to Nexstar’s KFDX.

According to the hotel website, the Sandman Signature Fort Worth Downtown Hotel has 245 rooms and was built in 1920 as the “Waggoner Building,” named after cattle rancher and oilman William Thomas Waggoner. The building has been listed on the National Register of Historic Places since 1979.

This is a developing story; The Associated Press contributed to this report.