A charter bus carrying students from a high school was rear-ended by a semi-truck on an Ohio highway Tuesday morning, leaving three people dead and 18 others injured, according to an emergency official.

Five vehicles were involved in the crash, including a Pioneer Trails charter bus that was transporting students from the Tuscarawas Valley Local School District in eastern Ohio, Licking County Emergency Management Agency Director Sean Grady said. There were a total of 57 people onboard, he said.

Lt. Nathan Dennis of the Ohio State Highway Patrol confirmed that people were killed in the crash, but he declined further comment since they were still notifying the victim’s families.

The bus was carrying Tuscarawas Valley students and chaperones to an Ohio School Boards Association conference in Columbus, Superintendent Derek Varansky said.

“Right now, our focus is on getting in touch with our Tusky Valley families who had loved ones on the bus and providing support to our entire school community,” Varansky said in a Facebook post.

The conference was canceled after organizers learned of the crash.

“Given this devastating news, we have canceled our conference. Right now, our focus is on providing support to Tuscarawas Valley. That includes making grief counselors from our trade show available,” said Jeff Chambers, the association’s director of communication services.

The accident occurred shortly before 9 a.m. on Interstate 70 West in Licking County, near the Smoke Road underpass and about 26 miles (42 kilometers) east of Columbus. The cause was not immediately known.

The injured were being treated at seven hospitals.

In a statement, Pioneer Trails, the charter bus company, confirmed there was an incident involving one of its buses Tuesday morning.

“Pioneer is fully cooperating with the authorities as we work to find the cause of the accident,” the company’s statement said. “Our thoughts and prayers go out to all of those impacted by this accident. As this is an ongoing investigation, there will be no further comments.”

The American Red Cross of Central and Southern Ohio said it fulfilled a request for more blood from one hospital in the area, sending 30 units to a hospital in the Mount Carmel Health System, said Marita Salkowski, regional communications director. A center was set up at a United Methodist Church in Etna for bus passengers not in need of medical attention to go to and contact loved ones, she said.

Numerous emergency responders were at the scene, and Ohio Department of Transportation cameras from the area showed smoke coming from the crash site. Police officers were blocking the entrance ramps to I-70 East and West near the scene of the accident, increasing traffic along the road leading to the interstate. Dozens of emergency response vehicles were still at the scene of the accident several hours after it occurred.

Mickey Lymon, an investigator with the Licking County Coroner’s Office, said they had been called to the scene, but deferred other questions to the state police.

“This is our worst nightmare, when we have a bus full of children involved in a crash,” Ohio Gov. Mike DeWine said during a news conference at the scene. “Prayers go out to the families, everyone who was on the bus.”

It was the second recent fatal crash involving high school students on a charter bus. In September, two people were killed and several others injured when a charter bus carrying high school students to band camp veered off a New York highway.

(AP)