Christian Science Monitor reports: At least 50 people were killed today in two predominantly Shiite neighborhoods of Baghdad, underlining Iraq’s tenuous stability as a political crisis threatens to inflame stark sectarian divisions.

There were at least four explosions across Baghdad. The first attack took place in Sadr City, in northeast Baghdad, and killed at least a dozen people. A half-hour later, another bomb went off nearby, killing one, the Guardian reports. The neighborhood of Kadhamiya, home to an important Shiite shrine, was blasted by a pair of almost simultaneous bombs two hours later. Yesterday there were a series of attacks on the homes of police officers and a member of a Sunni militia with ties to the government.

No group has claimed responsibility for the bombings yet, but The New York Times reports that they “appear similar” to previous attacks carried out by the Sunni militant group Al Qaeda in Iraq. On Dec. 22, AQI staged a series of explosions throughout the capital that killed more than 60 people.

Two days before those attacks, the Monitor’s Dan Murphy warned of the growing parallels between trendlines of violence today, and the situation at the height of Iraq’s civil war.