Baghdad (AP) The death toll has risen to 63 in a massive Baghdad car bombing.

The U.S. Is blaming a Shiite militant “special group” for yesterday's attack. A military spokesman says the group was trying to re-ignite sectarian violence that swept through the area 18 months ago.

No group has claimed responsibility for the blast. But it took place in a Shiite neighborhood that was the scene of some of the bloodiest sectarian violence in 2006. That led to speculation that Sunni extremists may have been behind the bombing.

The U.S. Uses the term “special groups” to describe Shiite extremists backed by Iran.

The attack is the deadliest in Baghdad since early March. The Iraqi government says the bombing will stiffen its resolve “to defeat the terrorists and to maintain the security achievements.”