Secret Service says agent saw 'quad copter' fly into White House complex

(Reuters) - A U.S. Secret Service officer on duty at the White House early on Monday saw, and heard, a two-foot-wide commercial "quad copter" fly at a low altitude into the heavily guarded complex, crashing on the southeast side, the agency said.

"There was an immediate alert and lockdown of the complex until the device was examined and cleared," a Secret Service spokeswoman said in a statement, noting the incident happened at 3:08 a.m. ET (0808 GMT).

"An investigation is underway to determine the origin of this commercially available device, motive, and to identify suspects," she said.

(Reporting by Roberta Rampton; Editing by Susan Heavey)