Police were notified of the accident at about 7:15am.
Maj Kraisorn Bunprasop of Thalang Police, as well as Kusoldharm Foundation rescue workers, arrived at the scene in front of Ban Lipon School on Thepkrasattri Rd in Thalang to find two men lying on the road unconscious and bleeding heavily.
The two men were identified as Sein Than Si Thu, 27, who was driving the motorbike, and Than Zaw Oo, 41, who was the passenger.
Also at the scene were a damaged Honda Click motorbike and a bus carrying hotel employees with a dent at the rear where the licence plate is displayed.
Rescue workers administered first aid before taking the two injured men to nearby Thalang Hospital.
The bus driver, 48-year-old Suban Suksri, explained to police that he had picked up hotel employees from near Heroines Monument and was driving them to a hotel in Nai Yang.
Mr Suban said that the motorbike was going very fast before hitting the back of the bus.
Police gathered evidence and took Mr Suban to Thalang Police Station for further questioning.