LONDON (Reuters) - A major London underground station shut down briefly on Tuesday because of a fire alert that proved to be a false alarm, hours after police said three parcel bombs had been sent through the mail to other transport hubs in the city.

Kings Cross St Pancras underground station, an interchange that serves two long-distance rail stations, closed for about half an hour after reports a fire had broken out.

“We believe that it was a hoax call at one of the fire points,” a Transport for London spokeswoman said, adding that investigations into the cause of the alert were continuing.

A spokesman for London’s fire brigade said there had been a false alarm and that firefighters had established there was no fire within 10 minutes of arriving at 2144 GMT.

The underground station was the scene of a devastating fire in 1987 that killed 31 people.

Earlier on Tuesday, police said a parcel bomb sent to an office building at London’s Heathrow airport caught fire when opened but did not cause any injuries.

Two similar bombs were later found at an office building at London City airport and at the British capital’s busiest rail station, Waterloo.