Washington airspace alert sparks White House lockdown

The White House and US Congress were locked down for nearly an hour Tuesday over a suspected airspace intrusion over Washington, but hours later officials still had no explanation for what triggered the alert.

Major Andrew Hennessy, a spokesman for the North American Aerospace Defense Command, told AFP that "a track of interest" appeared on radars early Tuesday, sparking concern. "Something that gave off a signature that our radar registered" set off the alert, he said.