MUSCAT, Oman – Ordered to get inside and stay down, Oregon tourist Clyde Thornburg heard the pirates’ rifle shots hit the side of the luxury cruise liner – “Pop! Pop! Pop!” – then felt the ship speed up to escape.

At this port north of the pirate-infested Gulf of Aden, passengers told The Associated Press on Wednesday they had been warned of the danger even before they embarked, and the crew used a device that blasted painful high-decibel sound waves to keep the marauders at bay.

The attack on the nearly 600-foot-long cruise ship in the dangerous waters between Yemen and Somalia was the latest evidence pirates have grown more brazen, viewing almost any vessel as a potential target – even a large luxury liner with hundreds of tourists on board.

But the assault on the M/S Nautica lasted only five minutes Sunday, and the ship with about 650 passengers and 400 crew members sped away quickly and was not seized.

“We didn’t think they would be cheeky enough to attack a cruise ship,” said Wendy Armitage, of Wellington, New Zealand, shortly after disembarking for a daylong port stop in the Omani capital of Muscat.

During the assault, pirates on one of two skiffs fired eight rifle shots at the ship, according to its American operator, Oceania Cruises, Inc.

The captain ordered the passengers inside and accelerated the cruise liner quickly, leaving the pirates far behind in their 20- to 30-foot wooden speedboats, powered with twin outboard motors.

“I couldn’t see them shooting, but I heard them hitting the ship, ‘Pop! Pop! Pop!'” said Thornburg, of Bend, Ore. “It wasn’t really scary because the captain announced for the safety of everybody to get inside and get down, and by that time he was pouring on the coals to the ship and was outrunning them.”

In about 100 attacks off the Somali coast this year, 40 vessels have been seized. Thirteen remain in the hands of pirates.