ORLAND, Calif. -- Nine people were killed Thursday in a three-vehicle crash involving a bus carrying high school students on a visit to a college.

The crash has shut down north- and south-bound traffic on Interstate 5, authorities said.

The California Highway Patrol received a report of the crash at 5:41 p.m. Thursday, dispatcher Curtis Pahlka said.

"At this point there are nine confirmed fatalities," he said.

Glenn County Sheriff's Dispatcher Pauline Spooner said that the passengers on the bus were high school seniors on their way to visit the campus of Humboldt State University in Arcata, Calif., and that several people were airlifted to local hospitals with injuries.

"The Red Cross has set up a shelter for the ones who had minor" injuries, she said.

Humboldt confirmed in a statement on its website that the bus passengers were prospective students on their way to the college.

"Humboldt State University is getting word of an accident involving a charter bus that was bringing a group of prospective students to the university's April 12 Spring Preview Day," the statement said. "The bus collided with a FedEx truck."

Pahlka said it is not yet clear what caused the crash but that it involved the bus, a FedEx truck and a Nissan Altima.

The northbound lane of Interstate 5 was closed at 5:46 p.m., and the southbound lane was closed at 6:30 p.m.

No further details were immediately available about the identities of the dead.

"I don't have any details on the individuals yet," Pahlka said.