Danish military forces disrupted the takeover by pirates of a cargo ship in the Gulf of Aden today, marking the first time this has happened since a multinational armada deployed a year ago, a naval spokesman said.  Ten members of the Danish special forces clambered aboard the Antigua and Barbudaflagged Ariella from a dinghy but by that time the pirates may have already been scared off when a helicopter from a Danish warship Absalon buzzed the cargo ship.  The ship's 25 crew members — a Bulgarian, a Slovak, an Indian, 15 Filipinos, and 7 Ukrainians — had locked themselves in a secure room.  All are reported safe.  Cmdr.  John Harbour, spokesman for the European Union Naval Force, praised the NATO forces for their fast reaction and coordination with other forces in the area.  "This is the first (instance) where a warship has been able to send forces to stop a hijacking while it was in progress," Harbour said.  Cmdr.  Dan B. Termansen, the commander of the Danish warship Absalon, said that crew had reported seeing a pirate firing an automat ic weapon onboard their ship.  The crew "saw a ski f f approaching and made full speed ahead," he said.  "When they saw the f irst pirate onboard the deck, they fled to the safe room."  He could not say whether there were any pirates onboard the ship when he sent the special forces, he said, because the hatches were open and it was unclear where the gunmen had gone.  "I don't know if he jumped overboard when he saw the helicopter or later when he saw the special forces," he said.  "We searched the ship for hours and didn't find anybody."  But Cmdr.  Mikael Bill, head of the Danish Admiralty in western Denmark, said he does not believe there were any pirates onboard the ship when the special forces members arrived.