KABUL, Afghanistan  A well-coordinated assassination attempt on President Hamid Karzai by suspected Taliban insurgents at the Afghan national day military parade in central Kabul has turned into a moment of national embarrassment for the government, which has been pressing to take over responsibility for Kabul’s security from foreign troops.

Three people were killed Sunday in the brazen assault, ruining what was supposed to have been a proud moment for Afghan security forces. The ability of the attackers to get so close to Mr. Karzai, who escaped unhurt, suggested they had inside help.

The dead included a tribal chief and a member of Parliament who were in the reviewing stands near Mr. Karzai, and a 10-year-old boy caught in the cross-fire as militants and security forces aimed at each other, officials said. Eleven people were wounded, among them army officers, police officers and civilians, hospital officials said. Several suspects were arrested later.

The attack sent officials and foreign diplomats scrambling for cover in the stands and hundreds of soldiers running off the parade ground in disarray. Mr. Karzai was whisked out the back exit, and the ceremony was abandoned after Afghan security forces had spent weeks preparing and rehearsing.