TAIPEI (Taiwan News) – A non-commissioned officer is in intensive care after a Clouded Leopard armored vehicle hit him during training at a base in Hsinchu County, reports said Friday.

The officer named Lee (李), 23, was standing off to the left in front of the vehicle when it moved forward at an Army training and testing facility in Hukou, Hsinchu County, on Thursday, the Liberty Times reported. Even though he only reported sharp stomach pain, an examination at the Ton-Yen General Hospital in Zhubei found damage to his spleen and kidney.

After an emergency transfer, Lee underwent surgery at the Tri-Service General Hospital in Taipei, where his condition was reported as stable, the Sixth Army Corps said Friday. The officer was based at the Guandu Area Command in Tamsui, New Taipei.

The Army said it was investigating the cause of the accident. At the time, only the driver was on board, with an officer in front giving directions, and three others standing to the right of the vehicle. An initial theory suggested that tall grass in the area might have hampered the driver’s view.