More than 75 people were reportedly killed and over 200 injured in a suicide attack by the Islamic State (ISIS) on the shrine of Lal Shahbaz Qalandar in Sehwan in Pakistan's Sindh on Thursday evening.
Government officials said the crackdown would continue nationwide over the coming days, following a week of bloody terror attacks claimed by both Isis and a faction of the Taliban.
More than 20 children were believed to be among the dead.
"An I.S. suicide bomber set off his explosive vest against a Shia gathering at Lal Shahbaz Qalandar shrine in Sehwan, Sindh province", said the Amaq propaganda agency linked to the Sunni Muslim jihadist group. The first explosion took place in the basement reserved for ablution and the second in front of the shrine's main gate.
Pakistan's army chief issued a statement after the attack. "No more restraint for anyone", the army chief was quoted as saying.
The latest bombing comes after a week of terrorist attacks across the country - one of which was claimed by the Pakistan Taliban - and Pakistan has vowed to do more about its growing terrorism problem.
Two men comfort a mourner after the killing of his relative at the shrine Thursday.
Meanwhile, Amrullah Saleh, the former head of the National Directorate of Security said attacks such as that on the shrine, was a result of supporting terrorists by Pakistan.
The U.S. Department of State condemned the attack at the vehicle dealership, stating that the bombing showed ISIS's "utter contempt for human life and its efforts to sow discord and division among the Iraqi people". Gen. Asif Ghafoor's official Twitter account, read. The border has been closed since last night due to security reasons.
Lal Shahbaz Qalander is Pakistan's most revered Sufi shrine, dedicated to a 13th-century "saint" whose spirit is invoked by devotees in ecstatic dancing and singing rituals.
"We also offer our support to the Government of Pakistan as it works to bring the perpetrators of this crime to justice", U.S. State Department Acting Spokesperson Mark C. Toner said. Other terrorist attacks have been on Christian minorities, people of the Shia community or police and other public officials.
Sindh province until now had been insulated from a wave of terror attacks in Pakistan, including in the eastern city of Lahore and the northern tribal belt.