KABUL, Afghanistan — A powerful car bomb that exploded near the site where Afghan elders are set to vote on a long-term security agreement with the United States killed at least 10 people on Saturday, rattling central Kabul and underscoring the insurgency’s desire to prevent an American presence in Afghanistan beyond 2014.

The bomb exploded shortly after 3 p.m. near the gates of Kabul Educational University, as students and pedestrians were filtering through the area, police officials said. An Afghan Army Humvee patrolling the area was also struck, killing at least one soldier and wounding three others, according to witnesses and the spokesman for the Afghan Ministry of Defense.

As the area is cleared, more bodies are likely to be uncovered.

The scene around the gates of the school was one of devastation. More than a dozen cars were destroyed in the blast, which leveled structures and pulverized bystanders, leaving shattered glass, blood and pieces of flesh covering the ground. The attack occurred at a police checkpoint on the way to the university, which is near a major transportation hub. A large bus filled with people was shredded in the blast.

“Students and schoolgirls were passing,” said Dr. Ghulam Sarwar Zohair, an employee of a nongovernmental organization with offices nearby. “Lots of people got injured and probably killed.”