The province is often the scene of lawlessness, including clashes between police and drug dealers or militants.
Although it occurred in a remote region, the explosion comes at a time of heightened political sensitivity nationally, with just over two weeks before the
Fars news agency quoted witnesses saying the incident had been a suicide attack, and that a second bomb had been defused near the mosque. The reports could not be verified.
Its location on the borders of both Afghanistan and Pakistan make it a key route in the drugs trade.