Christians took to Cairo's Tahrir Square Monday to protest violence targeting two churches and an apartment building over the weekend. At least a dozen Egyptian Christians were killed after a mob attacked a church and set fire to an apartment building.

More than 200 more people were injured.

The churches were targeted after rumors circulated that a Christian woman was being detained in order to stop her from converting to Islam. The attacks, coming four months after a Coptic church in Alexandria was bombed, killing 21, has renewed criticism that Egyptian authorities don't do enough to protect Egypt's Coptic Christian minority.

Authorities arrested dozens of people and the Egyptian justice minister vowed that "an iron fist" awaits those who threaten national security. An emergency cabinet meeting reportedly opened the door for the death penalty to be applied for attacks on religious sites.

Reports say Salafists, an ultraconservative Islamist sect, instigated the rumors and the violence as a political ploy.

"They want to assert themselves in the political arena, and their means to do so is to highlight rumors of conversion cases of ladies," Youssef Sidhom, a Coptic newspaper editor, told the Washington Post. "That is their way of creating a buzz."

One witness outside the Virgin Mary Church in Cairo's Imbaba district said Egypt's political instability opened the door to Salafi violence, the Los Angeles Times reported. They feared Mubarak, he said. "But now there is no security and they are free to attack. They want to turn this neighborhood into a place of Sharia law. They want full control."

Copts have faced increased violence since Mubarak's ouster in February, with attacks on churches and individual Christians. In addition to the Tahrir Square protest, other Copts are trying to wage a sit-in at the state television station.