Pol Captian Watcharapong Thianpratham of Khlong Luang precinct got the call at 3.30am and led officers and rescue workers from the Ruamkatanyu Foundation and other groups to the scene at Km 35+100 of the Paholyothin Highway in Tambon Khlong 1.
They found many of the passengers still aboard the privately operated Bangkok-Phanomprai bus in the ditch, including two drivers who worked in shifts and were among the injured.
Five passengers including the baby had been killed instantly. One of the injured passengers, a woman whose name was not released, was pronounced dead at hospital.
The bodies were taken to Thammasat Chalermprakiat Hospital for autopsies.
The bus had left Roi Et’s Phanom Prai district at around 8pm on Saturday night, bound for Bangkok.