Airport opens after hours of chaos
San Francisco airport was thrown into chaos when a security check found evidence of explosives on a man's shoes.
Security checkers at the airport found the residue on the man's trainers as he checked in for a United Airlines flight.
The man told the staff it could have come from fireworks and left the checkpoint before they had completed their investigation.
Because the man was missing police ordered all domestic flights at the airport to be grounded.
Most of the gates closed to passengers as they tried to find him.
In December, Briton Richard Reid was arrested for allegedly attempting to blow up a flight from Paris to Miami using a bomb hidden in his trainers.
Police later reopened the airport after finding no traces of explosive. However, they were continuing the hunt for the man.
He was described as white and aged in his 40s by airport staff.
The explosives were detected when a gauze-like material was wiped across his shoes and put through a machine.
An airport spokesman said: "United is our largest carrier. It was not a good time for this to happen."
