The ship was reportedly attacked by up to three pirate skiffs at a time Somali pirates have hijacked a ship with at least 20 US crew on board, after what maritime officials described as a sustained night-time attack.The US-operated container vessel, Maersk Alabama, was seized in the Indian Ocean about 400 miles (645km) east of the capital, Mogadishu. The Danish-owned ship's crew members are believed to be safe, the European Union's maritime security force said. It is the sixth seizure in recent days, including a British and Taiwanese ship. Among the cargo of the 17,000-tonne Maersk Alabama was UN food aid destined for Somalia and Uganda. Pirates typically hold the ships and crews until large ransoms are paid by the shipping companies - last year the firms handed over about £80m (£54m). The huge increase in frequency of attacks has forced several navies to deploy warships in the Gulf of Aden. The BBC's Adam Mynott says in the past few weeks the warships have forced the pirates to switch the focus of their attacks further out into the Indian Ocean. Evasive actionIn a statement, the AP Moller-Maersk Group confirmed its ship had been "attacked by pirates and presumed hijacked" at around 0600 BST on Wednesday. "The vessel is deployed in Maersk Line's East Africa service network and was en route to Mombasa, when it was attacked approximately 500 km off the Somalia coast," the statement said. "Our initial concern is to ensure proper support of the crew and assistance to their families." Now the weather has improved, they're back in business again ICG's Rashid Abdi The lure of easy money Why are pirates getting away? The assault began late at night and apparently lasted for some five hours, according to maritime officials. The ship was attacked by up to three pirate skiffs at a time. Maritime officials say the ship took all possible evasive action before it reported that the pirates had boarded. It is believed to be the first ship with Americans on board to be hijacked...