At least 52 people have been killed as security forces stormed a Catholic church in Baghdad to free dozens of hostages.

On Sunday afternoon, the residents of Baghdad heard a loud explosion, believed to have been a car bomb, followed by a gunfire as a group of armed men began by attacking the Iraq Stock Exchange building and then took over the Catcholic church across the road, in which about 100 people have gathered for the evening Mass, ?the BBC reported.

According to Deputy Interior Minister of Iraq, Maj Gen Hussein Kamal, six attackers were among the people who died in the fighting. He added that the number of injured is between 58 and 62 and most of them were women.

The gunmen had reportedly demanded the release of jailed al-Qaeda militants.

The BBC reports that a military website, allegedly run by the Islamic State of Iraq, a Sunni militant umbrella group to which al-Qaeda in Iraq belongs, has posted a statement, claiming responsibility for the attack.

The statement reportedly said that Iraqi Christians would be “exterminated” if Muslim women in Egypt were not freed.

A witness who was inside the church at the time of the attack has stated that the gunmen “came into the prayer hall and immediately killed the priest,” as cited by the BBC.

The witness has also stated that the attackers beat the worshipers and put them in an inner hall. Security forces and helicopters have surrounded the building. The attackers contacted them by mobile phones and demanded the release of the Muslim women and al-Qaeda prisoners.

Negotiations led nowhere and the security forces stormed the church. Then, the gunmen fired grenades and detonated their suicide vests, according to witnesses.

On Monday, Pope Benedict XVI condemned the attack as “absurd.” He said he was praying for the victims “of this absurd violence, made more ferocious because it was directed against unarmed people gathered in the house of God.”