A school bus filled with children rolled over in a multi-vehicle crash Monday morning in central Florida, killing two and injuring multiple others, according to authorities.

The bus was traveling to a high school and carrying 39 passengers, including 37 high schoolers, the bus driver and the driver’s 9-year-old daughter, Polk County Sheriff Grady Judd said in a press conference Monday morning.

Two people died in the crash, including a tenth-grade girl on the bus and an individual in a Jeep involved in the crash, Judd said.

Five to seven trauma alerts were issued and multiple people are being treated at the hospital, including one in critical condition, according to Judd.

The crash occurred in Winter Haven, Florida, and was reported at about 6:15 a.m. on Monday, according to authorities.

A preliminary review of video footage shows that the school bus was driving in its lane when a white Chevy Malibu traveling the opposite direction drifted over the center line for unknown reasons, hitting the bus, Judd said. This caused the bus to crash into a silver Jeep head-on, he said.

Another vehicle was involved, bringing the total to four vehicles impacted by the crash, officials said.

“It was a horrible crash,” Judd said. “It was a terrible, tragic morning.”

Emergency helicopters flew some victims to the hospital, while others left in ambulances or private vehicles, according to the sheriff’s office.

High schoolers called their families on their cell phones to notify them of the crash as officials worked after the incident to reunite students with their families, officials said.

Traffic homicide investigators are responding at the scene and will continue to gather information throughout the day.

All information is preliminary and more details will be released in another press conference likely on Tuesday, according to Judd.

“It’s an incredibly tragic event that took place this morning,” Fred Heid, Polk County Public Schools superintendent, said at the press conference. “We drill for this with our students intentionally so that they know how to evacuate a bus in the event of an accident, and we are very, very fortunate today that more students were not seriously injured, including the driver.”

This is a developing story. Please check back for updates.