Swedish police partly evacuated Landvetter Airport near Gothenburg after fears that armed robbers had left explosives near one of the terminals.
The gang stole a "large sum" of money from a plane which was unloading foreign currency but left behind a box on the tarmac before escaping.
The robbers had smashed through a fence surrounding the airfield and driven onto the runway.
All international flights from the airport were delayed.
According to police they drove up to the SAS plane from London which was unloading foreign currency into a security van.
At least five robbers, some with assault rifles, held up baggage handlers who were unloading the crates of money, police spokeswoman Maria Rosenberg said.
"The robbery was extremely well organised. They are no beginners," said Hans Lippens, the police superintendent in charge of the investigation.
Police were alerted to the airport at 1230 (1130 GMT).
The gang used two getaway vehicles which were later found on fire some distance from the airport.
The plane was also carrying passengers who witnessed the robbery.
Ms Rosenberg said the passengers and other witnesses were being questioned while a police helicopter and several patrol cars were searching for the gang.
Domestic flights to and from the airport were not affected by the incident.
International arrivals were rerouted to the domestic terminal.