At Least 16 People Dead and Multiple Others Critically Injured After Bus Smashes into Guardrail and Flips Over

At least 16 people have reportedly died following a major bus crash in Indonesia.

The passenger bus was traveling on a tollway in Semarang, Central Java, early Monday, Dec. 22, when it slammed into a highway guardrail and overturned onto its side at around 12:30 a.m. local time, search and rescue official Budiono said, according to the Associated Press and local outlets The Jakarta Post and Pos Kota.

The bus was carrying 34 passengers and had departed from the capital, Jakarta, heading to Yogyakarta — roughly 360 miles away — when the crash occurred.

Budiono said the vehicle is believed to have been traveling at a “fairly high” speed, The Jakarta Post reported. “The bus was speeding and is thought to have lost control, hitting the road divider and eventually overturning,” he stated, per Pos Kota.

“The forceful impact threw several passengers and left them trapped against the bus body,” Budiono added, according to the Associated Press.

Fifteen people were pronounced dead at the scene, and another person later died in hospital, The Jakarta Post reported. Budiono also said 18 people were being treated in hospital, with five in critical condition and 13 seriously injured, the Associated Press reported.

Authorities said they are investigating what caused the crash. Central Java Police Chief Ribut Hari Wibowo said investigators are questioning the injured substitute driver, according to the outlet. The driver sustained serious injuries but has reportedly been able to communicate, and officials plan to test him for illegal drugs, per the Associated Press.