A double bombing at a historic Christian church in northwestern Pakistan has killed at least 75 people. The bomber struck as hundreds of worshipers walked out of church toward a food distribution area on the lawn outside.

The attack is one of the deadliest to target Pakistan’s Christian minority in years. No group has claimed responsibility for the attack, but it is widely assumed to be the work of a militant Muslim group.

The death toll has risen as rescue workers search the rubble. At least 100 people were wounded, and many are in critical condition.  

Local hospitals said they were running out of beds for the wounded – and running out of coffins for the dead.

Police say they are not yet sure if the attack was the work of two suicide bombers or one. It is possible that a single suicide bomber first threw one bomb, then detonated a bomb vest.

The bombs were packed with ball bearings or other metal objects aimed at maximizing injury.

Two Muslim security guards who were stationed at the church were apparently among the dead.

Pakistan’s Ulema Council, the country’s largest clerical body, condemned the blast and said it was “standing with our Christian brothers in this tragedy.”

Pakistan has been hit by many deadly attacks in recent months. A suicide bombing at a funeral in Quetta left 29 dead in August; just weeks earlier, gunmen burst into a hotel in northern Pakistan and killed nine foreigners.

A bombing at the U.S. Consulate in March killed 10 people. The Pakistani Taliban claimed responsibility for that attack.