For updates from Wednesday on the deadly Interstate 70 crash, follow this link.

ETNA, Ohio (WCMH) – Three teenagers were among six people who were killed Tuesday morning when a semi smashed into the rear of a charter bus carrying high school students, just one part of a fiery, five-vehicle crash.

The crash caused the semi to catch fire and smoke to pour out of the bus, which was carrying students from Tuscarawas Valley Middle-High School in northeastern Ohio to an event in Columbus. The accident took place on Interstate 70 east of the exit for State Route 310 and led to I-70 being closed in both directions for hours.

The Ohio State Highway Patrol reported the accident took place about 8:50 a.m. in the westbound lanes, and at least 20 people were taken to seven area hospitals. Images of the immediate aftermath sent to NBC4 showed the cab of the semi ablaze and rammed into the back of the bus.

Pronounced dead at the scene from the bus were John W. Mosley, 18, of Mineral City; Jeffery D. Worrell, 18, of Bolivar, and Katelyn N. Owens, 15, of Mineral City. Three people in a passenger car were also pronounced dead at the scene, troopers said: Dave Kennat, 56, of Navarre; Kristy Gaynor, 39, of Zoar, and Shannon Wigfield, 45, of Bolivar. Kennat was a teacher and Gaynor and Wigfield were parent/chaperones, the school district said.

“This is our worst nightmare when we have a bus full of children involved in a crash,” Gov. Mike DeWine said in an update near the crash site. “Our hearts go out and prayers to all the families, all those who were on the bus, everyone who was involved in the accident.”  

Watch: Gov. Mike DeWine on deadly I-70 crash

Troopers said three of the vehicles involved caught fire. The front was the bus was also severely damaged. Jennifer Homendy, chair of the National Transportation Safety Board, said the bus and an SUV with chaperones behind it had slowed on I-70 near the Etna exit because of an earlier accident when the semi came up from behind. But she cautioned her office was still determining the sequence of events in the chain reaction. An update was expected Wednesday afternoon.

The bus was occupied by a driver and 54 passengers who were students or chaperones. It was operated by Pioneer Trails of Millersburg, which told the Associated Press it was cooperating with investigators. The semi was operated by Mid-State Systems of Hebron, which declined comment to NBC4. A second commercial vehicle was involved in the crash, and troopers said drivers of both commercial vehicles were hurt but expected to recover, with one being taken to a hospital and the other treated at the scene.

Also taken to hospitals were the bus driver and a passenger in one of the other vehicles involved. The school district said 18 of its 20 students taken to hospitals were released by 10 p.m. Tuesday and that the other two students had serious by non-life-threatening injuries. Surviving bus passengers were taken to a church in Etna, where they were reunited with family.

I-70 was closed eastbound at State Route 310 and westbound at State Route 158 near Kirkersville. Traffic was being forced to exit, with U.S. 40 and State Route 204 both running parallel to I-70 to the north and south, respectively. The closure lasted through the afternoon and into the evening, with eastbound lanes reopening about 4:30 p.m. and westbound lanes, after emergency repaving work, about midnight.

Live: Traffic at I-70 and State Route 310

In a statement to families, Tuscarawas Valley schools Superintendent Dr. Derek Varansky said he had “devastating and heartbreaking news to report.” The school, known as “Tusky Valley,” is in rural Tuscarawas County about 15 miles south of Canton, and there are about 1,200 students in the entire district. Schools will be open on Wednesday, Varansky said.

“Though difficult, school will be in session,” he wrote in a Facebook post. “We do not want children home alone, yet we respect students and parents who wish for their child to remain at home.”

A vigil took place at the school’s football stadium Tuesday night.

The accident marked the second deadly bus crash involving students in the area since August. On the first day of school, a bus carrying 52 elementary students went off the road and rolled onto its side after a car in the other direction went left of center. An 11-year-old student in the Northwestern Local school district in Clark County died, and 23 students were taken to area hospitals. The driver of the car has been charged.

The Tuscarawas Valley bus was on its way to the Ohio School Boards Association conference in Columbus. The day’s events were canceled.

“Our focus is on providing support to Tuscarawas Valley,” an OSBA statement read. “That includes making grief counselors from our trade show available. We are praying for the entire Tuscarawas Valley family.”