Initial reports suggest the explosion took place during Urs celebrations when scores of people had gathered to pay their obeisance and many of them were performing dhamaal after evening prayers.
"A suicide bomber blew himself up after he was intercepted by police guards on duty outside the shrine, killing 18 people including three children under the age of 12 and two policemen, and wounding at least 27 others, 14 of them seriously", provincial home secretary Akbar Harifal told a news agency.
The incident took place in Jhal Magsi district of the province after a suicide bomber detonated his explosives close to a shrine.
Deputy Commissioner Asadullah Kakar confirmed that it was a suicide attack.
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Dr Rukhsana Magsi, the Medical Superintendent at Jhal Magsi District Hospital, earlier told ARY News that at least six bodies have been received while a huge number of casualties are feared.
The minister said the bomber tried to enter the shrine, but blew himself up when the on-duty policeman stopped him for frisking.
The local administration declared an emergency at hospitals in Sibbi and Dera Murad Jamali.
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Security forces have cordoned off the area.
The Islamic State Khorasan Province - the Middle Eastern group's affiliate in Afghanistan and Pakistan - has since released a statement claiming the attack, according to the US-based monitoring group SITE. He said terrorists have no religion and the killers of Baloch people are enemies of the state.
Local government official Ahmed Aziz Tarrar said 16 people were killed and over 30 wounded in the blast.
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