Three Thai railway workers were killed and four others injured Tuesday in a bomb blast as they were clearing debris from an earlier attack in the south of the country over the weekend, police said.
Workers were repairing tracks near Khlong Ngae station, near the Malaysian border, when the bomb went off at around 6:30 a.m., according to authorities.
Another bomb went off on Saturday, damaging a freight train at the same location. The detonation did not leave any injuries, but forced the closure of the route.
The investigation was still in its early stages and no suspects had yet been identified, according to police.
Bombings are not unusual in southern Thailand, where anti-government separatists have clashed with government forces in the past, though the violence has subsided in recent years.