THE HAGUE, Netherlands—A pilot accidentally set off a hijack alarm on a plane at Amsterdam's Schiphol airport on Wednesday, triggering a huge security operation by Dutch police.

Spanish airline Air Europa "deeply" apologized for the incident on board its flight from the Dutch capital to Madrid, which saw emergency vehicles swarm around the plane.

"False alarm. In the flight Amsterdam-Madrid this afternoon was activated, by mistake, a warning that triggers protocols on hijackings at the airport," the airline tweeted.

"Nothing has happened, all passengers are safe and sound waiting to fly soon. We deeply apologize."

The Dutch Royal Military Police had earlier said they were investigating a "suspect situation," but announced an hour later that the passengers and crew were "safely off the plane."

The plane was carrying 27 passengers, Dutch media said.

Pictures from the scene showed police vehicles and ambulances clustered around the plane while parts of the airport were cordoned off by the false alarm.

Schiphol is one of Europe's busiest airports, handling more than 70 million passengers a year, according to its website.