They were part of a five-member team that had started their patrol on Thursday.
On Sunday afternoon, the team had reached the Ban Khok subdistrict area when a bull began charging at them and hit squadron leader Woraphot Piraksa head-on.
Woraphot sustained injuries to his face, nose, mouth and body and also lost some teeth. Another team member Jiraphong Nakrabum also sustained some injuries.
National park chief Thongchai Rajabuakaw said he would have sent a helicopter to pick them up, but the injured would have had to walk for two and half hours to get to the landing spot.
Hence, he decided to send an ambulance, which had to be parked some 5 kilometres away. The injured were eventually evacuated by another team of rangers and delivered to Phetchabun Hospital in the early evening.