4 injured as school bus plunges off Texas highway

WOAI-TV A television image shows the bus separated from its chassis beneath Interstate 37 in San Antonio on Thursday. By Darlene Dorsey, Elsa Ramon and M. Alex Johnson, NBC News New in this version: Details on injuries Updated at 7:53 p.m. ET: Four people were injured when a school bus plunged 15 feet off an interstate highway in San Antonio on Thursday, authorities said. The bus had already dropped off most of its passengers and was carrying only three people — the driver, an adult monitor and a young boy — when it flew off I-37 into the parking lot of a Comfort Suites hotel in east San Antonio about 4:35 p.m. (5:35 p.m. ET). Darlene Dorsey and Elsa Ramon are reporters for NBC station WOAI of San Antonio. M. Alex Johnson is a reporter for NBC News. Follow him on Twitter and Facebook. All three people on the bus were taken by ambulances to University Hospital under "priority one" protocols, which are invoked when a patient has "possibly life-threatening injuries," said Christian Bove, a spokesman for the San Antonio Fire Department. A fourth person in a separate vehicle on the highway also was taken to a hospital with unspecified injuries. It wasn't immediately clear whether the two vehicles collided.  Authorities said that despite the precautionary protocols, none of the injuries was believed to be grave — mainly broken bones for the driver and the monitor and facial cuts for the child. No information about the identities of any of the victims was immediately available. Watch US News videos on NBCNews.com The bus was traveling north on the interstate when it veered off the side, completely flipped in midair and landed right-side up, shearing it from its chassis, which came to rest at a right angle to the main body of the bus, NBC station WOAI-TV reported. Sherry Chaudhry, the hotel's manager, told WOAI that gasoline had spilled all over the scene of the accident and that bystanders broke out the bus' windows to rescue the boy. Chaudhry said she was able to speak with the bus driver, whom she quoted as having said a car cut off the bus and forced it off the road. This is a breaking news story. Check back for more details. More content from NBCNews.com: Video: Could Border Patrol agent's death have been friendly fire? Almost-Eagle Scout denied award because he is gay Somalis 'should leave culture at door' remark by Maine mayor stirs outrage 'Business as usual': Congress asks VA to explain chronic late payments to student vets 7 bears killed in Montana after becoming dependant on humans for food Philadelphia student wearing Romney shirt told to 'get out of the class' Follow US news from NBCNews.com on Twitter and Facebook