An unmanned aerial drone owned by the Mexican government has crashed in an El Paso, Texas, backyard, prompting questions about how and why the surveillance aircraft entered U.S. airspace.
U.S. Border Patrol agents were the first to respond to the incident Tuesday after someone notified authorities of the crash, a Department of Homeland Security spokesman told ABC News. No one was injured.
"We recovered the UAV and returned it to the government of Mexico," said Demetrio Guerra with the Border Patrol's El Paso unit.
Guerra declined to speculate on the drone's mission, but sources said it appeared likely the device was being used by Mexican authorities to monitor illegal drug trafficking and human smuggling across the border.
Calls to the Mexican consulate in El Paso were not immediately returned. The Border Patrol declined to comment on the Mexicans' use of drones and whether the U.S. agency had been aware of their use.
The National Transportation Safety Board is now leading the investigation into why the drone fell out of the sky.
"We're collecting data at the moment on the purpose for the drone, the type of drone it was, and why it crashed," said NTSB spokesman Keith Holloway.
The NTSB has not dispatched any investigators to the scene, said Holloway, and the device has been returned to Mexico. Holloway said they are analyzing data collected by the Border Patrol.
Holloway said the NTSB has previously investigated crashes of unmanned drones on U.S. soil that belonged to the U.S. government or hobbyists. He could not confirm that this was the first crash by a foreign-owned drone.
The device, identified as a "mini orbiter UAV," is a wing-shaped aircraft that can fly stealthly at altitudes up to 18,000 feet and remain in the air three to four hours, according to the website for manufacturer Aerospace Defense Systems . The drones can typically be operated by a single individual.
John Callahan, an engineer for a private defense contractor familiar with drones, said the Mexican aircraft likely ran out of battery power or lost radio connection with its operator preceding the crash.
"If these devices lose a radio link or for some reason go too far, they typically go into 'lost link mode' and either await a signal, flying in circles, or turn around and go back to base," he said. "In this case that either didn't happen or it ran out of battery."
Some models of the mini orbiter are equipped by parachutes. It's unclear if one deployed in this case.
Vincent Perez, spokesman for Rep. Silvestre Reyes, D-Texas, former chief of the U.S. Border Patrol-El Paso sector and chairman of the House Select Committee on Intelligence, said the congressman is gathering more information on the incident.
"Our law enforcement has a very close relationship with Mexican authorities," said Perez, who suggested U.S. officials may be working with their peers south of the border to determine what happened.
The U.S. Border Patrol has been using unmanned drones to patrol border areas since 2005.
Perez said he expects the NTSB and Department of Homeland Security to release additional details on the incident later today.
ABC News' Matt Hosford contributed to this report.