This Aug. 15, 2014 photo released by Colombia's Army press office shows Colombian Army Gen. Ruben Dario Alzate in Colombia. Colombian President Juan Manuel Santos suspended peace talks with the South American nation's largest rebel group after Alzate was taken captive on Sunday, Nov. 16, 2014. The U.S.-education soldier and two others were intercepted while traveling by motor boat along a remote river in western Colombia. A fourth soldier managed to flee and reported that the captors were members of the 34th front of the Revolutionary Armed Forces of Colombia, or FARC. AP Photo/Colombian Army press office This Aug. 15, 2014 photo released by Colombia's Army press office shows Colombian Army Gen. Ruben Dario Alzate, left, reaching to shake hands with a soldier in Bogota, Colombia. BOGOTA, Colombia (AP) - A massive search operation was under way Monday for a Colombian army general whose surprise capture by leftist rebels prompted President Juan Manuel Santos to suspend two-year-old peace talks. Gen. Ruben Dario Alzate, dressed in civilian clothes and without the heavy security befitting his high rank, was snatched Sunday by gunmen along with two others while visiting a hamlet along a remote river in western Colombia. A soldier who managed to flee in the group's boat, and reportedly had advised the general against traveling deep into the jungle, said the rebels belonged to the recalcitrant 34th Front of the Revolutionary Armed Forces of Colombia, or FARC. It's the first time in a half-century of fighting that the guerrillas have taken an army general captive. It couldn't have come at a worse moment for Santos. Even before the general's capture, frustration with the slow progress of peace talks in Cuba and the guerrillas' refusal to wind down attacks had been building. Earlier this month, the FARC captured two soldiers during intense fighting in northeast Colombia - it has since offered to free them - and killed two Indians who confronted rebels hanging up revolutionary banners on their reservation. Calling Alzate's abduction "totally unacceptable," Santos ordered government peace negotiators not to travel Monday to Cuba for the next round of peace talks until Alzate and the two others - an army captain and a female lawyer advising the army on a rural energy project - are freed. "The FARC is responsible for the life and safety of these three people," Santos told journalists after midnight after meeting with his top military commanders before they left for the western city of Quibdo to oversee rescue efforts. The FARC considers captured military personnel to be prisoners of war even though it freed all soldiers in its control and swore off the capturing of civilians on the eve of talks in 2012. It also has been clamoring for a cease-fire while peace talks continue, something Santos has rejected for fears it would allow the guerrillas to regroup after years of battlefield defeats at the hands of Colombia's US-backed military. The FARC's 34th Front is among the group's most entrenched and dangerous fighting units, based in the dense, water-logged jungles around Quibdo where a slew of criminal gangs and drug-traffickers also operate. Its fighters repeatedly violated unilateral cease-fires declared by the FARC leadership in Havana during elections and Christmas holidays. A spokesman for the FARC in Havana declined to comment, saying the rebels' negotiators were still investigating the incident. Santos, who was re-elected in June, has staked his presidency on reaching a deal with the FARC. But he's struggled to overcome doubts from conservative opponents and members of the military who fear he's ceding too much power to the rebels. "While the FARC talks about peace in Havana, here they're committing all sorts of atrocities," said former Peace Commissioner Camilo Gomez, adding that the talks could unravel without a major overhaul to demand the FARC demonstrate its commitment to peace. This could be the straw that breaks the camel's back. In a sign of growing tensions with his military, the president Sunday night demanded to know why one of Colombia's most distinguished soldiers apparently violated military protocol and set off on the Atrato River in the dangerous zone dressed as a civilian without bodyguards. So far no explanation has been provided and residents in the 800-person hamlet of wooden shacks where the group was taken told local media they didn't know about the visit. Analysts say that the capture appears to have been accidental and not a planned ambush. All the same, securing the general's release could be difficult: after a decade of heavy losses inflicted by the US-backed military, the FARC leadership's operational command over its estimated 8,000 troops has been greatly reduced and just getting messages to the frontlines could take several days. Alzate, 55, is among Colombia's most-decorated soldiers. A graduate of the U.S. Army War College and Command and General Staff College in Kansas, he previously oversaw the military's anti-kidnapping unit. In January, Santos named him commander of the newly established Titan Task Force, a 2,500-man counterinsurgency force operating from Quibdo. Associated Press writers Camilo Hernandez in Bogota and Andrea Rodriguez in Havana contributed to this report. Follow Joshua Goodman on Twitter: @APjoshgoodman