Officials with the state prosecutor's office spotted two bodies amid the wreckage of the plane, the government office, which is responsible in Colombia for investigating deaths, said Thursday. U.S. Embassy officials said they had no comment on the report.
The Cessna was flying from Bogota to the Florencia area, 235 miles to the south, when radio contact was lost eight minutes before landing, Colombia's Civil Aviation agency said.
CBS News State Department Reporter Charles Wolfson reports the plane carried four U.S. citizens and one Colombian. All were involved in a counter-narcotics operation.
Earlier, a Colombian official, speaking on condition of anonymity, said that it was feared they had been taken by rebels. Other officials suggested those aboard the Cessna may have been hiding, if they survived the crash, to avoid capture by the rebels.
The spokesman said the American government plane, a single-engine Cessna 208, "crashed near Florencia during an attempted emergency landing shortly before 9 a.m. this morning. The cause of the crash was apparently engine failure."
After getting word of the crash, U.S. officials scrambled rescue teams to the sweltering plains of the region, but at least one report said rebels had captured those aboard and announced, "We have them! We have them!" in an intercepted radio transmission.
There was no statement from the Revolutionary Armed Forces of Colombia, or FARC, Colombia's main leftist rebel group. A Colombian military official reported the transmission and said FARC rebels had apparently found the plane.
U.S. officials refused to discuss the mission or identities of those aboard the single-engine Cessna, which went down as it approached Florencia, 235 miles south of Bogota, the capital. The Colombian Armed Forces' high command said the plane was on an intelligence operation.
It was not clear which arm of the U.S. government operates the crashed plane. A host of U.S. agencies and government contractors are in Colombia. They operate radar stations that track drug-smuggling flights, fumigate drug crops with airplanes and assist Colombian security forces in other anti-drug operations. Sources said those aboard the crashed plane were not Drug Enforcement Administration agents.
If the survivors were captured, it would mark the first time in Colombia's decades-long civil war that Americans on U.S. government business had been taken by the insurgents.
Cropdusting pilots contracted by the U.S. State Department have been waging a massive fumigation campaign against the drug crops. But the State Department contractor, DynCorp, said its personnel were not aboard the crashed plane.
Still, DynCorp spokeswoman Caroline Longanecker said the company was helping with rescue and recovery. DynCorp maintains search-and-rescue teams aboard Black Hawk helicopters in its area of operations as a precaution.
A Colombian military official said Colombian military Black Hawks were also being sent to the area, but then were ordered to return, with U.S. officials being in charge of the case.
The crash comes as Washington moves beyond simply fighting drug trafficking — which provides profits for rebels and paramilitaries, to helping the Colombian government directly battle the insurgents.