A bomb killed at least 72 people on Wednesday at a busy market in eastern Baghdad's Sadr City slum, police said, six days before US combat troops are due to withdraw from Iraqi towns and cities. About 127 people were wounded by the blast in the poor, mostly Shi'ite Muslim area. A witness said the explosion tore through a part of the Mraidi Market where birds are sold, setting stalls ablaze. Bloodshed has dropped sharply across Iraq in the past year, but militants including Al-Qaeda continue to launch car and suicide bombings aimed at undermining the government and reigniting sectarian conflict. Wednesday's market bombing came four days after the US military formally handed control to local forces in Sadr City, where US and Iraqi forces fought fierce battles against Shi'ite militiamen in the spring of 2008. Raad Latif, who owns a shop near the blast site, said the bomb appeared to have been on a trailer attached to a motorcycle. “The blast was very big and loud. After we heard it, we closed our shops and rushed to help the injured,” Latif said. Initially the security forces kept residents back to allow ambulances and police vehicles into the area, he said. “After a while they came to their senses and allowed us to help as much as we could ... the scene was horrific,” he said.