By Ray Sanchez, Sophia Saifi and Adeel Raja
ISLAMABAD, Pakistan (CNN) — At least 60 people were killed in a suicide attack Thursday at Pakistan’s packed Lal Shahbaz Qalandar shrine in the southern city of Sehwan in Sindh province, a police official said.
As many as 250 others were injured, according to Khadim Hussain Rind, the Hyderabad Police inspector general.
The Islamic State Khorasan, ISIS’ affiliate in Afghanistan and Pakistan, claimed responsibility for the attack in a phone call to CNN.
The Amaq news agency, which is affiliated with ISIS, reported the attack was carried out by a suicide bomber in an explosives vest.
Thousands of worshipers, including families with their children, had gathered at the iconic shrine for the Sufi ritual of Dhamal, which involves music, chanting and prayer. The shrine is more than 800 years old.
Prime Minister Nawaz Sharif called the attack “brutal.”
“I have directed all the state institutions to mobilize all resources for rescue and relief after this brutal terror attack on Lal Shahbaz Qalandar’s shrine,” the Prime Minister said in a statement.
The spokesman for the Pakistani military blamed operatives from Afghanistan for a recent spate of attacks on the country.
The spokesman, Maj. Gen. Asif Ghafoor, tweeted: “Recent Ts (Terrorist) acts are being exec (Executed) on directions from hostile powers and from sanctuaries in Afghanistan. We shall defend and respond.”
In another tweet, he urged the country to remain calm: “Your security forces shall not allow hostile powers to succeed. We stand for our nation.”
He later announced on Twitter that the Pakistan-Afghanistan border was “closed with immediate effects till further orders due to security reasons.”
The attack comes days after a bomb exploded during a protest in Lahore, Pakistan, on Monday, killing at least 14 people and injuring 59 more, according to government spokesman Malik Ahmad Khan.
Jamat-ul-Ahrar, a splinter group of Pakistan’s Tehreek-i Taliban (TTP) — also known as the Pakistani Taliban — claimed responsibility for that attack in a statement emailed to CNN.
CNN’s Sophia Saifi and Adeel Raja reported from Islamabad, with Ray Sanchez writing and reporting in New York. Journalist Saleem Mehsud also contributed to this report.