At least seven people were killed and some others were injured in the US state of New Mexico on Thursday when a tractor trailer crashed into a bus, CNN reported. “We do expect that number to rise,” New Mexico State Police spokesperson Officer Ray Wilson said.

The police said preliminary information indicated that the tractor-trailer blew a tire and crossed the median, crashing into the oncoming traffic, AFP reported.

“There are multiple serious injuries and passengers [are being] transported,” New Mexico State Police said. “Officers and EMS [emergency medical services] are actively working and assessing the scene.”

The bus was carrying 49 passengers and heading to Phoenix in Arizona. Dozens of passengers were seen trying to climb out of the windows of the bus after the crash.

“We are fully cooperating with local authorities and will also complete an investigation of our own,” said spokesperson of Greyhound bus service Crystal Booker in a statement, according to CBS News. “The total number of injuries has not been determined at this time. The cause of the incident has not yet been determined.”