WSJ

"The Secret Service said it believes a hobbyist accidentally crashed a drone onto the White House grounds early Monday, an incident that prompted a lockdown and delivered a wake-up call over the potential terrorism threat of unmanned aircraft.

"The person flying the 2-foot helicopter that crashed called the Secret Service after the incident was widely reported and has been cooperating with agents, the agency said. Authorities didn't identify the person.

"The Secret Service said the crash appears to have 'occurred as a result of recreational use of the device,' but officials said the agency is still following up on other leads.

Continue reading the WSJ article, and a follow-up WSJ article entitled "Criminals, Terrorists Find Uses for Drones, Raising Concerns," both of which feature interviews with Dr. Humphreys.