A tour bus carrying high school students on a college visit collided with a FedEx 18-wheeler and burst into flames on Thursday in Northern California, killing nine people and injuring dozens more, according to the authorities. The State Highway Patrol said the vehicles collided around 5:45 p.m., when the FedEx truck crossed a center divide and crashed into the bus on Interstate 5 in Orland, a town about 100 miles north of Sacramento. Traffic on the highway was shut down in both directions. Police did not identify the victims, but said that the fatalities included students. It was not immediately clear what caused the truck to cross to the divide, the highway patrol said. The bus was carrying 46 passengers, many of whom were being treated for burns and other injuries, the highway patrol said. A Nissan Altima was also involved in the collision, but no one in that vehicle was injured. The passengers were high school students from Los Angeles on their way to visit Humboldt State University in Arcata, near the Oregon border, the college and students' families said.