ISLAMABAD, Pakistan — Two suicide bombers attacked crowds of Pakistanis visiting a Sufi Muslim shrine in the country’s largest city, Karachi, Thursday night, killing at least 10 people and wounding 65 others in an attack that reminded the nation of extremists’ ability to strike virtually at will.

The blasts appeared to be timed to coincide with when crowds are largest at a shrine for Abdullah Shah Ghazi, a revered eighth-century saint of the Sufi doctrine of Islam. The shrine sees its biggest crowds on Thursday nights and draws people from throughout Karachi and the rest of Sindh province.

Television footage showed grisly images of pools of blood on the shrine’s concrete and wailing children in bloodied tunics being rushed to local hospitals.

President Asif Ali Zardari, who was in Karachi on Thursday, condemned the attack.

“”The relentless attacks on ordinary Pakistani citizens by those who want to impose an extremist mindset and lifestyle upon our country will not deter our government,”” said one of Zardari’s top aides, Farahnaz Ispahani. “”We remain committed to fighting these murderers and expelling them from our land.””

Authorities in Karachi said the bombers detonated their explosives outside the shrine’s main entrance, where visitors must pass through an electronic security gate. Sindh Home Minister Zulfiqar Mirza said as a result of the blasts, all shrines in Karachi will be shut down for the next three months.

No one had claimed responsibility for the attack as of Thursday evening. However, shrines and mosques belonging to adherents of Muslim doctrines opposed by militants have been frequent targets of the Pakistani Taliban, the country’s homegrown insurgency, and Sunni Muslim extremist groups like Sipah-e-Sahaba. During the summer, twin suicide blasts killed 42 people visiting Pakistan’s most popular Sufi shrine, Data Darbar, in the eastern city of Lahore. And earlier in the year, a team of gunmen and suicide bombers killed 93 people in attacks on two mosques belonging to the minority Ahmadi sect.

Islamic militant groups regard the Sufi discipline of Islam to be tantamount to heresy. Several terrorist attacks this year have also targeted the country’s Shiite Muslim minority.