 An explosion at a Texas hotel in Fort Worth on Monday littered downtown streets with large section of building and debris and injured at least 11 people, including one who was in critical condition, authorities said investigators believed the blast was caused by natural gas, said Bureau of Alcohol, Tobacco, Firearms and Explosives spokesperson Sarah Abel, who was briefed by local police. Officials said at a news conference that other people were seriously injured and the rest had minor injuries. Local 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. �There is a smell of gas in the area and there are windows and things that were blown outside of the structure,� said Craig Trojasek, a spokesman for the Fort Worth Fire Department. Right now, through our investigation, it looks like it is more of some kind of gas leak. 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. �Downstairs? Well, that's their hotel but the rest of them are downstairs.