Suspected rebels set off a car bomb on Friday outside a violence-wracked town in eastern Colombia, killing five civilians, including two children, police said.
Four others, including a soldier, were wounded in the explosion near the Saravena airport and a Colombian military base where US Special Forces have been training Colombian troops, General Luis Alfredo Rodriguez said.
A Colombian army patrol was passing by when the bomb exploded, Rodriguez said. A 3-year-old girl and 13-year-old boy were among those killed, he said.
Saravena, 365km northeast of Bogota, is in Arauca state, one of Colombia's hottest war zones where rebels and paramilitary forces are fighting over the region's rich oil resources.
Authorities offered a reward of 50 million Colombian pesos (US$18,000) for information leading to those responsible.
The attack came the same day that security for President Alvaro Uribe was doubled after reports indicated the nation's largest rebel group may be planning suicide attacks to kill the leader.
According to military intelligence, Jorge Briceno of the Revolutionary Armed Forces of Colombia, or FARC, 15 days ago ordered his troops to prepare suicide commandos to assassinate Uribe, promising large amounts of money to their families.
The FARC has allegedly sent hostages, and even unwitting children, on deadly bomb attacks in the past, but its own men have never willingly participated in suicide missions.
Briceno, who is considered the military chief of the FARC, launched the plan because "the guerrillas are fearful of the possible re-election of President Uribe," army Gen. German Galvis told RCN Television.
Last month, Colombian lawmakers presented a bill to Congress that, if approved, would allow Uribe to run for re-election in 2006. The president is currently limited to one term under Colombia's constitution.
The FARC has already attempted to assassinate Uribe numerous times. During his campaign in April last year, a bomb placed under a bridge exploded as his caravan passed by in the Caribbean coastal city of Barranquilla, killing three bystanders. A mortar attack during his inauguration a year ago left 21 people dead.
The president travels with more than 50 bodyguards and dozens of bomb-sniffing dogs. Hundreds of soldiers and police officers secure areas where he makes public appearances while helicopters scope out the scene from overhead.
Despite the latest threats, however, Uribe plans to continue traveling around the country -- even in areas where the FARC has a strong presence.
"We are conscious of the fact that there are risks, but we are also preparing for all possibilities with the security measures," General Teodoro Campo, the nation's police chief, told Caracol Radio.
Meanwhile, the leader of the nation's right-wing paramilitary groups -- foes of the leftist rebels -- urged the US to send a delegate to Colombia to assist in peace talks with the Colombian government.
Carlos Castano, chief of the United Self-Defense Forces of Colombia, said the delegate could help speed along the promised demobilization of some 13,000 fighters in a statement posted Thursday on the group's Web site.
The US representative could also clear up the fate of paramilitary leaders, such as himself, wanted for extradition on drug charges in the US, Castano said.
"The most serious of the difficulties facing the [peace] process ... is the extradition requests," Castano said.