Seven bombs placed inside apartment buildings across Baghdad killed at least 49 people and decimated residential neighborhoods in an onslaught that Iraqi and U.S. security officials blamed on al Qaeda-linked militants.

The explosions are the second coordinated large-scale bombings in the last three days, fueling fears that insurgents are taking advantage of Iraq's post-election political vacuum to sow chaos and spiral the country back to civil war. In the last week, more than 100 people have died in numerous attacks around Baghdad alone.

No claim of responsibility has been made for the bombings this week, but a resurgence of al Qaeda — or other militant groups — capable of planning and carrying out such large-scale assaults casts doubt over Iraq's security situation and how the country will cope when U.S. troops begin their withdrawal this summer.

Prime Minister Nouri al-Maliki, who ran on a law-and-order platform during last month's elections that his political list narrowly lost, urged Iraqis to stand united against "terrorists" who "want to push the country into civil strife."

In a written statement released Tuesday night, he pledged to intensify the numbers of patrols around Baghdad. Apparently addressing the growing sense of unease in the capital in the wake of the devastating attacks, he called on citizens and the media not to undermine the morale of the country's security services.

Baghdad security spokesman Major General Qassim al-Moussawi blamed the wave of violence on remnants of al Qaeda, an opinion shared by U.S. military officials in Iraq. Yet, U.S. officials played down the bloodshed. They described the string of attacks as last-ditch efforts of a struggling terrorist network, not a signal that the country was ramping up towards the same internecine violence that paralyzed the country in 2006 and 2007.

"In the last few weeks and last few months, the (Iraqi Security Forces) have [achieved attrition in the ranks of] Al Qaida leadership. Every time there are attacks, they learn more from these attacks," said Lt. Col. Eric Bloom, spokesman for U.S. forces in Iraq.

Such optimism was not shared by many Iraqis who gathered to help tend the wounded and pull bodies from the crumpled remains of multi-story concrete apartment blocks located in both predominantly Shiite neighborhoods and some of the capital's mixed districts.

Officials said the blasts across Baghdad had killed at least 49 people and wounded more than 160. In the Alawi neighborhood, near the National Museum, an apartment building with a tea shop on the roof was reduced to rubble by the bomb placed inside. "Nobody knows now how many people were killed," said Ali Khadem, 27.

The apparently coordinated explosions hit the capital two days after nearly simultaneous suicide car bomb attacks against embassy compounds killed 41 people and wounded more than 200. Over the weekend, 25 more people were murdered in what appears to be a targeted killing of Sunnis working against al Qaeda.

U.S. military statistics show that the number of attacks and civilian casualties per month are continuing a downward trend. But, with Iraq is a state of political flux after last month's parliamentary elections, tensions are high about whether the country's political parties will respect a peaceful transition of power.

No political party won a majority of seats in parliament, and results show a country still deeply divided on sectarian and ethnic lines.