At least 15 people were killed and 16 others injured, including five children, when a passenger bus veered off the road and plunged into a deep ravine in Sri Lanka late Thursday, police said Friday.

Police spokesman Frederick Wuttler reported the accident occurred near the town of Wellawaya, about 280 kilometers east of Colombo, where the bus fell nearly 1,000 feet into a gorge.

All injured passengers were rushed to nearby hospitals, while authorities launched an investigation into the cause of what has been described as a “tragic accident.”

According to the Associated Press, the crash ranks among the deadliest road accidents in the country in recent years.