BOGOTA, Colombia (AP) _ Two gunmen on a motorcycle fatally shot Colombia's most popular satirist today while he was driving to the radio station where he was a morning host, police said.

Jaime Garzon was shot in the head as he neared the offices of Radionet in his green Jeep Cherokee, national police commander Gen. Rosso Jose Serrano said.

Though best known for his stinging satires of Colombian personalities on television and radio, Garzon also promoted efforts to achieve peace with leftist rebels. He served on several occasions as an intermediary between leftist rebels and the families of kidnap victims, and he organized rebel news conferences.

``It could be he was murdered for his humanitarian efforts,'' Serrano said.

Colleagues cried on the air as they discussed the killing, which occurred just blocks away from the station shortly after 6 a.m. Taps played in the background.

Aida Luz Herrera, Radionet's news director, said President Andres Pastrana had canceled a trip to Colombia's interior because of the killing.

Pastrana, a longtime friend of Garzon who had worked with him as a fellow broadcaster, announced that the government would offer a reward for information leading to the killers.

``It wasn't just that he made us laugh. Jaime in large part identified with the sentiments of Colombians, with what we were thinking,'' Pastrana said.

On his daily improvised show on Radionet, Garzon played a character called Heriberto de la Calle, a humble shoeshine man with a caustic tongue. Two years ago, he had the most popular political satire show on Colombian television.

There was no immediate claim of responsibility, but Garzon's colleagues said they thought Colombia's right-wing paramilitary militias were to blame. The killing comes amid stepped-up rebel and paramilitary violence as a peace initiative Pastrana launched last year falters.

``Here we're all very confused, in a lot of pain,'' Herrera said. ``Feeling impotent.''