(The Hill) — A flight heading to Los Angeles had to make an unscheduled stop on Monday when the pilots mistakenly believed there was an attempt to breach the cockpit. This confusion arose because flight attendants were forced to knock on the secured cockpit door due to a breakdown in the plane’s communication system.

SkyWest flight 6569, which took off from Eppley Airfield in Omaha, Nebraska, returned to the airport around 7:45 p.m. local time. The Federal Aviation Administration (FAA) reported that an emergency was declared as the pilots couldn’t establish contact with the cabin crew.

The flight, operated by SkyWest on behalf of American Airlines, managed to cover less than 40 miles before it had to head back to Omaha.

Upon landing, it was revealed that the issue stemmed from a malfunction in the inter-phone system, prompting the crew to resort to knocking on the cockpit door, according to the FAA.

SkyWest has yet to release a statement regarding the incident.

The captain apologized to the passengers after landing.

“We weren’t sure if something was going on with the airplane, so that’s why we’re coming back here,” the captain said. “It’s going to be a little bit. We have to figure out what’s going on.”

Video footage of the flight shows police officers boarding the plane after the emergency landing, as police vehicles approached on the tarmac.