July 9, 2009 Violence spikes in Iraq, testing the country's security forces Play video

(NECN/ABC) - Attacks across Iraq today mark the worst violence since U.S. combat troops pulled out of the country's major cities and towns. A double suicide bombing in Northern Iraq killed at least 34 people and wounded dozens more. The attacks are testing Iraq's own security capabilities just one week after the US handover.

In Sadr city, Iraqi police secured the scene after two separate bombs exploded near a market in the early morning hours. Six people were killed and dozens more wounded. In northern Iraq not long after there was a double suicide attack, killing at least 33 people.

"Apparently the first attacker detonated an explosives vest. As people were coming in to help the wounded another large explosion went off, leading to these 33, we've had reports of even more deaths than that," said BBC Correspondent Gabriel Gatehouse.

The wave of violence underscores the challenges Iraqi forces are facing with the absence of U.S. troops patrolling in the cities. Just over a week ago, on June 30th, Iraq celebrated what the Prime Minister called a "victory," full responsibility for their own national security.

Vice President Joe Biden during a surprise trip to Iraq defended the withdrawal. "We have met the commitment of the time table negotiated by the last administration with the Iraqis and we are totally confident that it is the right thing to do," said Vice President Joe Biden on July 4th.

Five days after Mr. Biden made that statement

the hospital in Sadr city was filled with an unwelcome yet familiar scene. In the Karrada district of Baghdad one man said he was sitting in his bookshop when a bomb exploded, targeting officials from the Central Bank. Later, Iraqi forces cleared the area and cleaned up to start the day again, on their own.

Gloria Riviera reports for ABC News