Two Filipino women were injured by a landslide while using the stairs at Haew Narok waterfall in Nakhon Nayok province about noon on Wednesday.
Chaiya Huaihongthong, chief of Khao Yai National Park, said the landslip fell onto a steep stairway leading to the second tier of the waterfall.
The two injured women, Cecille Silverso and Mary Ann Angel Pacis, both aged 38, were in a group of seven tourists visiting the waterfdall, five adults and two children.
They were taken to Chaophya Abhaibhubejr Hospital in Muang district of Prachin Buri for treatment of their injuries. One had a broken leg. Both women remained conscious on the way to the hospital.
The Khao Yai National Park chief said it was the first landslide recorded in the area and occurred after five days of rain.
Haew Narok is a three-tier waterfall, the largest in Khao Yai National Park. It has now been closed indefinitely to the public for safety reasons with the arrival of the wet season.