Flights at an airport in the US state of Virginia were delayed on Tuesday and its terminal building evacuated after a "serious" threat was phoned in, officials and local media said.
On its Twitter feed (@Flack4RIC), Richmond International Airport said it had "received a threat by phone, deemed serious enough to evacuate the terminal as a precautionary measure."
Sniffer dogs swept the terminal, baggage areas and parking zones, while travelers were advised to check with their airlines for rebooking options, before the all-clear was given.
"Update: #RIC terminal, including airline desks and security screening, re-opened to the public," tweeted the airport four hours after receiving the undisclosed threat.
The Richmond News-Leader newspaper, on its website (www.timesdispatch.com), said at least a dozen morning departures had suffered delays, plus a smaller number of arrivals, affecting hundreds of passengers.
More than half a dozen airlines serve the state capital's airport.
Elsewhere, a "small electrical explosion" prompted a brief evacuation of a concourse at Hartsfield-Jackson Atlanta International Airport in the southern state of Georgia.
"Passengers were evacuated but have returned," said the airport on its Twitter feed (@Atlanta_Airport). "No injuries reported... Full power has been restored and all operations have resumed."
Local television station WGCL traced the explosion to a ramp-level maintenance shop.