The driver of a school bus in the US that was filled with elementary students when it crashed in Chattanooga, killing at least five children, has been arrested and faces charges including vehicular homicide.
Describing the incident as "every public safety professional's worst nightmare", Chattanooga Police Chief Fred Fletcher told a news conference that 24-year-old bus driver Johnthony Walker had been charged with five counts of vehicular homicide as well as reckless driving and reckless endangerment.
Investigators were looking at speed "very, very strongly" as a factor in Monday afternoon's crash, Mr Fletcher added.
Police said five children were killed in the crash. Earlier in the day, Hamilton County District Attorney Neal Pinkston told news outlets that six had died. The Associated Press was not immediately able to reach officials to clarify the discrepancy.
Thirty-five students ranging from kindergarten age through to fifth grade were on board when the bus flipped on to its side and wrapped around a tree. The bus was the only vehicle involved in the crash, but Mr Fletcher said the scene was complicated and covered a significant area.
Bloodied Woodmore Elementary School students lay on stretchers, while others walked away dazed with their parents after the crash, local news outlets reported. More than 20 children needed hospital treatment for their injuries, according to Mr Fletcher.
Emergency responders needed almost two hours to get all the children off the bus.
Television cameras showed emergency vehicles still there late into the night, and the National Transportation Safety Board tweeted that a team would be heading to Chattanooga on Tuesday morning to investigate.
Television stations reported that people lined up to donate blood and some donors were asked to make appointments for Tuesday.
Kirk Kelly, interim superintendent for Hamilton County schools, said classes would be held Tuesday with counsellors available for students and staff.
Mr Fletcher said the families of the children who died had been notified but police would not release their names because they were juveniles.
"Our hearts go out, as well as the hearts of all these people behind me, to the families, the neighbourhood, the school, for all the people involved in this, we assure you we are doing everything we can," the police chief said.
At the state Capitol in Nashville, Tennessee, Governor Bill Haslam called the crash "a tragic event" and offered assistance.
"We're going to do everything we can to assist in any way," he said. "It's a sad situation any time there's a school bus with children involved, which there is in this case."