Two officials working for a bus operating company pleaded not guilty Thursday to charges stemming from a crash in 2016, which killed 15 people in a mountain resort town, as they faced court in the first hearing of their trial.

Misaku Takahashi, 60, president of the operator ESP, and Tsuyoshi Arai, 53, an operations manager at the time of the crash, denied they were guilty of professional negligence resulting in death or injury.

In the early hours of Jan. 15, 2016, an ESP bus chartered for a ski trip, driven by 65-year-old Hiroshi Tsuchiya, careened off a road in the town of Karuizawa, Nagano Prefecture, after hitting a guardrail at a speed of 96 kilometers per hour. Tsuchiya was one of 15 people aboard who died, and 26 others were injured.