BOGOTA, Colombia (CNN) -- A former Colombian justice and interior minister was the apparent target of an explosion that killed three people in the Colombian capital on Tuesday, President Juan Manuel Santos said, according to CNN affiliate Caracol TV. Former minister Fernando Londono was among at least people 19 injured.

Londono's driver and head of security were among the victims, the president said in televised remarks.

"I want to condemn this in the strongest terms," he said, adding that the motive for the attack was unknown.

Londono served as minister from 2002-2004. He was being treated at a hospital, Santos said.

A witness, German Diaz, said all the windows from a bus were blown out and there was blood all over the scene.

There was panic at the scene, he said. People were crying.