Investigators on Sunday hauled away the wreckage of a U.S. plane that crashed on an intelligence-gathering mission in the Colombian jungle, where a frantic search was underway for three Americans who were on board.

The Americans apparently were kidnapped by the Revolutionary Armed Forces of Colombia, or FARC. A fourth American and a Colombian army sergeant were executed at the crash scene.

The U.S. government has not identified the people on the flight or disclosed their mission.

A Colombian soldier on a mountain road across the river from the crash scene said the investigators were Americans. The U.S. embassy has said the plane went down in the lush jungle mountains after experiencing engine trouble.

National Police Director Gen. Jorge Campo said Sunday the plane was struck by gunfire from the ground, but that did not cause the crash.

A suspected rebel captured by authorities was sent to Bogota on Sunday to be interviewed about the case, said Alonso Velasquez, director of the local prosecutor's office.

The plane crashed in a cattle pasture carved out of the mountain jungles in the tiny hamlet of Ano Nuevo. The aircraft, seen from across the river, appeared damaged badly, lying near a home perched on the side of the mountain.

While the investigators sifted through the charred remains of the single-engine Cessna, half-a-dozen military helicopters circled overhead and some 600 Colombian soldiers protected the site and investigators.

A corporal who declined to give his name said peasants in the region refused to talk about what they may have seen.

"The people there don't talk," he said. "I asked them what happened and they only told me that they heard an explosion. They're scared."

The crash site is near the border of a former rebel safe haven granted to the FARC during three years of failed peace talks. The Colombian government revoked the safe haven last year and sent troops back into the area. Security forces are in the major towns, but the FARC, Colombia's largest rebel group, still controls much of the countryside.

A priest in the diocese of Florencia, which includes the tiny hamlet, said many peasants in the region fear the guerrillas.

"The countryside is very controlled at the moment," he said. "There are areas where in order to enter or leave, you have to ask for permission from the guerrillas. [The peasants] don't say anything out of fear."

The priest, who asked that his name not be used, said he had received death threats from the rebels. He worried about the captured Americans.

"I think they're living through the most difficult moments of their lives," he said. "As representatives of the American government, it may be more complicated."

The United States has given Colombia almost $2 billion in the past three years, mostly in military aid. The aid initially was restricted to anti-drug operations. The rebels finance their fight through drug trafficking and the priest said much of the region farms coca plants, the base for cocaine.

The rebels consider Washington's support for the Colombian government an act of war and have said they would target U.S. citizens and interests.

Washington recently lifted the aid restriction to allow Colombian forces to use U.S.-purchased equipment and U.S.-trained troops to battle the rebels directly. Last month, about 70 U.S. Green Berets were sent to an embattled northeastern state to train Colombian counterterrorist troops.

Separately, authorities said Sunday the bodies of two missing Colombian soldiers were found buried in Venezuela, near the border with Colombia.

The two soldiers disappeared Feb. 1 from the Venezuelan village of El Amparo, across the border from Arauca state, Gen. Carlos Lemus said. Colombian soldiers based in Arauca frequently cross the border in their free time.

Authorities believe the two were kidnapped by the National Liberation Army, or ELN, Lemus said. The ELN is Colombia's second-largest rebel group.