Three Thai railway workers have been killed and four others were hurt after a bomb exploded as they were clearing the wreckage of an earlier attack over the weekend in the country’s south, police said.

The workers were repairing tracks near Khlong Ngae station, not far from the Malaysian border, when the bomb exploded at about 6.30am (11.30pm GMT on Monday), according to authorities.

On Saturday, another bomb derailed and damaged a freight train at the same location, causing no injuries but forcing the closure of the route.

Police said the investigation was in its early stages and they were still working to identify any subjects.

Bombings are not uncommon in southern Thailand, where anti-government separatists have clashed with government forces in the past, though there has been a general decrease in violence in recent years.