Twelve people were killed Saturday when Muslims attacked a church in Cairo, in the second incident of its kind since March. The attack set off violent clashes that ended in hundreds of injuries and almost 200 arrests.

The incident began when a Muslim mob attacked the St. Menas church after hearing rumors that a Christian woman married to a Muslim man had been kidnapped and was being held in the church. There does not appear to have been truth to the rumors.

The mob threw firebombs at the church, chanting, “With our blood and our souls we will defend you, Islam.” The crowds attacked nearby homes and shops with firebombs as well.

Many in the mob carried knives and machetes, and witnesses said they heard gunfire, which apparently came from rooftops.

Clashes broke out as Christians attempted to defend the church. In total, at least six Muslims and three Christians were killed, and more than 230 people were injured, 11 of them critically.

Police attempted to quell the violence, but fighting continued. Later at night a Muslim mob set fire to the nearby Virgin Mary church. On Sunday morning the mob continued the attack, setting fire to a six-story residential building over rumors that Christians had fired on Muslims from its windows.

Many Muslims living near the two churches expressed anger at the Muslim mob, and several Islamic clerics denounced the violence as well.

Similar clashes took place in March. The earlier clashes were also sparked by a rumor of Muslim-Christian love; in that case, Muslims stormed a church and set it on fire after hearing that a Muslim woman was romantically involved with a Christian man, a relationship prohibited by Islamic law, which allows Muslim women to marry only Muslim men.

On New Year's Day a church in Alexandria was bombed, killing 23 people.

A Christian advocacy group in Britain warned in October that Egypt's Christians face a growing threat to their safety. In March, American Christians began to work to raise awareness of the plight of their co-religionists in the Middle East.