Transcript for Drones shut down London airport

major airport shutdown. All flights halted tonight after a drone scare, seen 50 times today alone. Officials calling it tonight a deliberate act. The chaos at gatwick, can selling hundreds of flights, stranding tens of thousands of passengers. American travellers among them. ABC's James Longman is there tonight. Reporter: Every single plane at one of Europe's busiest airports grounded tonight. A drone, police say, is deliberately disrupting operations, leaving tens of thousands stranded. Helicopters circling. Officers with long guns on alert. A massive operation underway to locate the mystery pilot whose been sending a drone in and out of gatwick air space since our power to find those responsible. Reporter: In the terminals, chaos. Please, please -- Reporter: This departure board says it all. Passengers stuck on grounded planes for hours, or diverted as far away as Amsterdam. This New York student, angry and disappointed. Just shoot this thing out the air. Reporter: This simulation shows what a drone could do to a moving plane. Watch again. The experiment demonstrating why officials are taking extraordinary measures. The British military now going in. Their specialized equipment is hoped could down the industrial-type device. Let's get to James Longman tonight. Officials are not calling this terror-related, but they do say the drone flights are, quote, highly targeted, James? Reporter: That's right, David. And because of that, this airport is shut with no real idea as to when things will be back to Normal. Tonight, a police spokesman did tell me they have not ruled out shooting that drone down. David? All right, James Longman at gatwick airport in the uk tonight.

This transcript has been automatically generated and may not be 100% accurate.