Communist rebels in southern Colombia ambushed a military convoy on Wednesday, killing 10 soldiers in a hail of gunfire and explosions, authorities said. The troops were traveling by truck on a remote jungle road in Putumayo state, one of Colombia's biggest cocaine-producing regions some 300 miles south of Bogota, when they came under attack, said Adm. Mauricio Soto, the Colombian navy commander. Only one Marine in the convoy survived. Soto blamed the attack on guerrillas of the Revolutionary Armed Forces of Colombia, or FARC, which has been battling to topple the government here for 40 years. The group funds itself through drug trafficking, kidnapping and extortion.In February, the FARC launched some of its boldest attacks in two years on the military throughout the country, killing more than 50 soldiers and calling into question government assurances that the group was being weakened. Also Wednesday, police said suspected FARC fighters attacked a squadron of U.S.-supplied drug-fumigation planes and two escort helicopters in southeast Colombia, lightly damaging several of the aircraft and wounding a pilot.