Suspected leftist rebels fired four mortar shells here today, apparently aimed at the U.S. Embassy and the building housing the attorney general's office. Two people on a busy street were slightly wounded.

The 60mm mortars fell on a grassy area outside the attorney general's office, causing panic among workers and passersby but little damage. The site is a few blocks from the heavily fortified U.S. Embassy compound.

Authorities found two unfired mortars at the nearby National University after troops stormed the campus. Authorities said they thought the mortar attack was launched from the campus by urban rebels. Officials at the embassy declined to comment.

President Alvaro Uribe, whose inauguration in August was rocked by mortars launched by members of the Revolutionary Armed Forces of Colombia, pledged to catch the attackers and offered an $18,000 reward for information leading to their arrest.

Colombia is gripped by a 38-year war that pits Marxist rebels against right-wing paramilitaries and the military. Washington brands the rebels and paramilitaries "terrorists."

Bogota is usually spared the bloodshed of the war, as combat has been confined largely to the countryside. Rebels occasionally launch attacks in the capital using car bombs and explosives.