In this photo provided by the Chattanooga Fire Department via Chattanooga Times Free Press, Chattanooga Fire Department personnel work the scene of a fatal elementary school bus crash in Chattanooga, Tenn., Monday, Nov. 21, 2016. In a news conference Monday, Assistant Chief Tracy Arnold said there were multiple fatalities in the crash. (Bruce Garner/Chattanooga Fire Department via Chattanooga Times Free Press via AP)
In this photo provided by the Chattanooga Fire Department via Chattanooga Times Free Press, Chattanooga Fire Department personnel work the scene of a fatal elementary school bus crash in Chattanooga, Tenn., Monday, Nov. 21, 2016. In a news conference Monday, Assistant Chief Tracy Arnold said there were multiple fatalities in the crash. (Bruce Garner/Chattanooga Fire Department via Chattanooga Times Free Press via AP) Credit: Bruce Garner

Chattanooga, Tenn. — Bloodied students lay on stretchers, while other children walked away dazed with their parents after an elementary school bus crash that killed six on Monday in Chattanooga.

Chattanooga Police Chief Fred Fletcher said the crash was “every public safety professional’s worst nightmare.”

The bus was carrying 35 children from Woodmore Elementary, students in kindergarten through fifth grade, when it crashed about 3:30 p.m., turned on its side and wrapped around a tree.

Fletcher said police were interviewing the bus driver to determine what happened and told reporters later that investigators were looking at speed as a possible contributing factor. The bus was the only vehicle involved, he said.

Twenty-three students were taken to hospitals, Fletcher said. He did not have information about the extent of injuries. Media reported it took about two hours to get the last children off the bus.