A car bomb exploded Wednesday at the entrance to a fruit and vegetable market in south Baghdad, killing 15 people and wounding about 40, police and hospital officials said, in the latest sign of rising attacks.

The blast, which occurred about 7 a.m. at the Rasheed market in the city's southern Dora area, follows a sharp increase in violence in Iraq last month, raising concern that militants have regrouped after suffering sharp setbacks in fighting over the last two years.

Hours later, another car bomb exploded in the capital's Karradah district, killing two people and wounding six, police said. The bomb apparently targeted a police patrol but missed.

Most of the recent bombings have taken place in Shiite areas, suggesting Sunni militants such as Al Qaeda in Iraq are responsible. The Rasheed market is in a mainly Sunni area, but the farmers who bring their crops there are predominantly Shiites.

Some survivors of the Wednesday blast complained that security forces were too lax in searching trucks used by farmers to bring produce to the market.

"The security personnel are not searching the farmers who bring their vegetables to the market," survivor Raad Hussein told Associated Press Television News. "They search only private cars."

Kamil Lahmoud, a Shiite farmer from Mahmoudiya, said he had just sold his produce and was inside an office collecting his money when the blast happened.

"I was injured slightly in my head and left hand," he said. "I went out and saw many people covered with blood and bodies scattered everywhere."

Police and hospital officials reported the casualty tolls but spoke on condition of anonymity because they were not supposed to release the information.

Despite the rise in attacks, the Iraqi government has ruled out asking U.S. combat troops to remain in Iraqi cities after the June 30 deadline for their withdrawal.

The U.S.-Iraq security agreement that took effect this year calls for American combat troops to leave urban areas by the end of June, with all U.S. forces out of the country by the end of 2011.