Militants blew up a railway track in an attack that killed two children in Pakistan's southwestern province of Baluchistan on Thursday, police said.
Police did not say who was behind the attack, but nationalist rebels, struggling for greater autonomy, have fought a low level insurgency for decades in Baluchistan, the country's largest but least populous, and poorest province.
"Miscreants planted a bomb near the track which went off and blew up a four feet-long piece of the track and killed two kids," Manzoor Tareen, a railway police officer in Quetta, told Reuters.
The children had been playing near the track on the outskirts of Quetta, the provincial capital.
The blast disrupted rail links with the rest of the country, but railway police say the damage would be repaired quickly and service would resume within a few hours.
The new government has initiated talks with Baluch militants and released several Baluch leaders in a bid to put an end to the violence.
Nationalists accuse Punjab, the richest and largest of Pakistan's four provinces, of exploiting their mineral resources, particularly oil and gas.
Militants target government installations, security forces, gas pipelines, railway tracks and electricity pylons.