A remote-controlled bomb on a motorcycle exploded as revelers left a disco in a southwestern city early Sunday, killing 10 people and wounding 48 others, army officials said.

The bomb went off outside the disco around 4:00 a.m. in the upscale Zona Rosa district of nightclubs and bars in Florencia (search), 200 miles southwest of the capital, Bogota (search). A 9-year-old boy and two policemen were among the dead.

Gen. Luis Alberto Ardila, the commander of the army's 2nd Division in Florencia, said he suspected the country's largest rebel group, the Revolutionary Armed Forces of Colombia (search), in the blast.

"We've had two attacks like this in less than a year carried out by the FARC," Ardila told Radio Caracol.

"Although the explosive wasn't powerful, it caused a lot of casualties because it was placed in front of a disco which a lot of people were exiting," he said.

The attack comes amid a FARC campaign to disrupt state and mayoral elections scheduled for Oct. 25. The guerrillas have hit energy and rail targets and bridges in the past few weeks.

Security forces have responded by carrying out mass arrests of suspected rebel fighters, leading to the seizure of several arms caches.

Florencia police chief Col. Rafael Parra immediately offered a reward equal to $17,500 for information leading to an arrest.

He called for residents to donate blood as the injured, some of whom were in serious condition, flooded the only emergency hospital in the city of 100,000 people.

"This is a small city that does not have the infrastructure to treat so many injured," Parra said.

The FARC has been battling to overthrow the government for nearly four decades. The conflict, which pits the FARC and a smaller rebel group against outlawed right-wing paramilitary factions and the government, claims an estimated 3,500 lives every year.

Florencia is one of the largest cities on the border of a former rebel safe haven the size of Switzerland that was the site of peace negotiations. Talks collapsed in February 2002, and the government withdrew the region's status as a safe haven