Passengers wait in the South Terminal building at Gatwick Airport, after the airport reopened to flights following its forced closure because of drone activity, in Gatwick, Britain, December 21, 2018. REUTERS/Toby Melville

LONDON (Reuters) - A drone attack that crippled London’s Gatwick Airport for three days may have been carried out by a disgruntled current or former airport employee, British police believe, according to The Times.

Britain’s second-busiest airport, Gatwick was forced to close its runway before Christmas when drones flew near the site south of London.

Officers have collected 130 witness statements and made 1,100 door-to-door inquiries, pulling in other police forces to help, the newspaper said.

The witness statements suggested the drone was operated by someone who knew the airport layout well. The attacker hid the drone behind buildings where it could not be taken down by anti-drone equipment.

The operator also knew to fly the drone past air traffic control, where a ban on mobile phones would keep people from filming it.

“[The drone pilot] knew the blind spots for it, where it could not be ‘hit’,” a government official told the newspaper. “It was clearly someone with really good knowledge of Gatwick, someone who had worked there. Hypothetically, it could have been a disgruntled employee.”

Police did not respond to a request for comment.