Two trams collided and overturned in Thailand's Khon Kaen Zoo, killing five on board and injuring more than 50, local police said Sunday.
A 2-year-old girl was crushed and died at the scene. Four more died en route to the hospital.
Photos from the scene show the both trams skidded off the road and turned sideways.
A preliminary investigation by the police found that the accelerator on one tram got stuck. The driver then lost control of the vehicle while going downhill and ran into the tram in front.
Due to the zoo's hilly terrain and large area of about 3,000 acres, visitors usually take the tram or rent a private golf cart to travel around.
Located 500 kilometres north-east of Bangkok, the zoo houses many exotic animals such as white lions and white tigers.