Police said the attack occurred on a No-133 bus when it stopped at a bus stop in Bang Plee Muang Mai in Samut Prakan.
The three are students of Kanchanapisek Technical School in Samut Prakan.
Police said about 20 students of the Kanchanapiske school were riding the bus to school but when the bus stopped at the spot, they encountered some 20 students of Bangkok Technology School. One of the students from the rival school threw a bomb at them.
Police said Ekkaluck Sinual, 18, lost his right hand after he grabbed the bomb and tried to throw it back. The bomb exploded in his hand.
Shrapnel from the bomb also injured Wiwat Putnor, 18 and Wirwat Torsup, 18.
The Nation


