40 people killed and 50 were injured in a suicide blast in Afghanistan. Photo credit to ABC news.

Kabul, Afghanistan – 40 people were killed and more than 50 wounded in the attack as worshipers were leaving Friday morning prayers marking the beginning of Eid al-Adha.

About 20 bodies, some in police uniform, lay in front of the mosque’s gates as smoke billowed above. The attack, at around 9am local time on the first day of Eid, came just before President Hamid Karzai repeated his call for the Taliban to join the government.

According to Ministry of Interior spokesman Sediq Seddiqi, the death toll was likely to rise given the size and timing of the explosion.

There was no immediate claim of responsibility, but Seddiqi laid the blame for the attack squarely at the feet of Taliban leader Mullah Omar.

Eid al-Adha, knows as Feast of Sacrifice, is considered a happy holiday for Muslims. It celebrates the day when God appeared to Abraham known as Ibrahim to Muslims in a dream and asked him to sacrifice his son as an act of obedience.

Coming at the start of the Eid holiday, the attack gathered fast condemnation from neighboring Pakistan as well as the United States.

The NATO-led International Security Assistance Force denounced the attack. “I condemn this heinous act, which is an affront to human life, to religious devotion and to the peaceful aspirations of the Afghan people,” said General John R. Allen, ISAF’s commander. “This violence undertaken at a place of worship, and during Eid, once again shows the insurgency’s callous hypocrisy and disregard for religion and faith.”

Pakistan’s Foreign Ministry vowed to stand by Afghanistan in the fight on terrorism.

The U.S. Embassy in Kabul said the attack demonstrated “the insurgency’s lack of respect for religion, faith and its disregard for the safety and security of the Afghan people.”

Violence is intensifying across the country 11 years into the Nato-led war, sparking concerns over how the 350,000-strong Afghan security forces, often the target of the Taliban, will manage once most foreign troops leave.