CHATTANOOGA, Tenn. (WBIR) -- Police in Chattanooga have confirmed that multiple children were killed in a crash Monday afternoon involving a school bus filled with elementary school children.

Officials previously said there were 35 students on board and 23 patients were transported to the hospital after what was described as a "horrible" crash.

Tennessee Highway Patrol Colonel Tracy Trott confirmed on Twitter that the crash was deadly.

"My heart goes out to the families of the children that were killed & injured in the school bus crash in Chattanooga this evening," Trott tweeted.

As of 5 p.m., Chattanooga Police Chief Fred Fletcher said there were a total of 35 kindergarten through fifth grade students on the bus.

"A bus crash involving school children is every public safety professional's worst nightmare. But it's also the thing that we all train for and you have police, fire, EMS, and our partners out here doing everything they can to rescue victims and support the families of those who've already been treated," Chief Fletcher said.

The Chattanooga Fire Department said around 5:30 p.m. that the last patient was just extricated from the bus.

The school bus driver is cooperating with police and their investigation, Fletcher said during a press conference.

School officials said the bus was from Woodmore Elementary.

The fire department described it on Twitter as "very serious" and Chattanooga's mayor called it "horrible."