The suicide bomber struck the pilgrims during a dhamaal (ritual dance) after the evening prayers. The perpetrator blew himself up inside the shrine hall under the dome, near its Golden Gate. The bomber also threw a grenade which failed to explode. The bomber, believed to be an Afghan national, had bypassed the security check at the shrine.
At least 20 children were believed to be among the dead. The bomber used a suicide jacket, with the ball bearings in the jacket acting as shrapnel and causing casualties.
The injured and deceased were immediately shifted to the Taluka Medical Hospital which was not equipped with a trauma centre to deal with emergency cases. The medical facilities in Sehwan were basic, and some of the injured were in critical condition. A state of emergency was declared for all hospitals in the neighbouring areas.Pakistan Navy helicopters and a Pakistan Air Force aircraft C-130 were dispatched for rescue operations.
Hours after the attack, law enforcement agencies launched a nationwide crackdown and search operation, during which over 100 militants were killed and scores arrested. Several insurgents were confronted in Sindh and Khyber Pakhtunkhwa. Weapons, including hand grenades, were recovered from their hideouts. Police arrested a suspected facilitator in connection to the Sehwan attack from Johi, a town in Sindh's Dadu District.
The next morning, the shrine's caretaker continued the daily tradition of ringing the shrine's bell at 3:30 A.M., and said that he would not be intimidated by terrorists. The shrine's dhamaal, or meditative dancing ceremony, resumed the evening following the attack.
Prime Minister Nawaz Sharif condemned the blast, and said that "an attack on the shrine of Lal Shahbaz Qalandar is an attack on the progressive and inclusive future of Pakistan." A statement released by the military's Inter-Services Public Relations (ISPR) stated that the army chief, General Qamar Javed Bajwa, had ordered that immediate assistance be provided to civil authorities. Bajwa said "Each drop of the nation's blood shall be revenged, and revenged immediately. No more restraint for anyone."
ISPR spokesman, Major General Asif Ghafoor, tweeted: "Recent terrorist acts are being executed on directions from hostile powers and from sanctuaries in Afghanistan. We shall defend and respond". A few hours after the incident, the Pakistan-Afghanistan border was sealed indefinitely for security reasons. On 17 February, the Pakistan Army summoned Afghan embassy officials to the General Headquarters and handed over a list of 76 insurgents hiding in Afghanistan. The army demanded that Kabul take "immediate action" or have them "handed over to Pakistan". The same day, army chief Qamar Javed Bajwa made a telephone call to the general commander of U.S. forces in Afghanistan, John W. Nicholson, and expressed concern over such incidents in Pakistan linked to safe havens in Afghanistan. Bajwa stated "Such terrorist activities and inaction against them are testing our current policy of cross border restraint" and urged Nicholson for cooperation in dismantling the militant networks, in addition to briefing him about the list of wanted terrorists. Later, Pakistani security forces destroyed a dozen Jamaat-ul-Ahrar camps across the border in eastern Afghanistan, and killed over a dozen militants including a top trainer of suicide bombers. The strikes were confirmed by Afghan sources, who said that several Pakistani artillery rounds had hit Nangarhar Province's Lal Pur District and that "15 to 20 terrorists, among them Commander Rehman Baba, have been killed and many more injured." The Afghan foreign ministry also protested the shelling by Pakistan on its territory.
Afghanistan: President Ashraf Ghani condemned the attack, stating that "terrorists once again proved that they have no respect for Islamic values". Chief Executive Abdullah Abdullah also condemned the attack and offered sympathy to the families of victims and people of Pakistan.
Belarus: Ambassador Andrei Ermolovich condemned the Sehwan blast while expressing solidarity with Pakistan. He also said that Belarus stands with Pakistan in its efforts for elimination of terrorism.
China: President Xi Jinping condemned the attack and offered sympathy to the Pakistani people. He said that China "will stand ready to firmly support Pakistan in its effort to fight terrorism, maintain national stability and safeguard its people”. Chinese Premier Li Keqiang also expressed shock and condemned the attack.
Japan: A statement issued by the Ministry of Foreign Affairs said that “Japan is shocked and saddened by the suicide attack".
United States: Acting State Department deputy spokesman Mark Toner said the U.S. condemned the suicide bombing and offered its "support to the Pakistani government as it works to bring the perpetrators of this crime to justice". He added: "We stand with the people of Pakistan in their fight against terrorism and remain committed to the security of the South Asia region."