WASHINGTON (AP) — FBI Director James Comey said Thursday that the agency used its aircraft above Ferguson, Missouri, last year at the request of local law enforcement to help keep track of unrest on the ground.

Comey did not go into details during a House Judiciary Committee hearing on Thursday, including how long the surveillance lasted.

But in response to questioning, he said the FBI uses airplanes during investigations of specific suspects in criminal, terrorism and espionage investigations and when local police request help during a "developing situation" or emergencies such as riots. He said the planes were never used for mass surveillance.

"We don't fly planes around America looking down to see if somebody might be doing something wrong," Comey told the panel.

He said the FBI's deployment of aircraft in Ferguson, where police and protesters clashed following the August 2014 police shooting of an unarmed black 18-year-old, was similar to the help offered during riots in Baltimore last April that followed the death of Freddie Gray after grievous injuries suffered in police custody.

"If there is tremendous turbulence in a community, it's useful to everybody — civilians and law enforcement — to have a view of what's going on," Comey added. "Where are the fires in this community? Where are people gathering? Where do people need help? And sometimes the best view of that is above rather than trying to look from a car in the street."

The Associated Press reported in June that it had traced at least 50 aircraft back to the FBI and had identified more than 100 flights in 11 states over a 30-day period last spring. Law enforcement officials said at the time that the FBI hid its aircraft behind fictitious companies to protect the safety of the pilots and aircraft, shielding their identities from would-be suspects on the ground.

Comey said the FBI doesn't think warrants are generally required for the planes, in part because the aircraft do not capture or record the contents of any communications on the ground.

"The law is pretty clear that you don't need a warrant for that kind of conversation," he said.

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