Special forces on a Portuguese warship seized explosives from suspected Somali pirates after thwarting an attack on an oil tanker, but later freed the 19 men. Hours later and hundreds of miles away, another band of pirates hijacked a cargo ship, a NATO spokesman said Saturday, AP reported. Pirates are now holding 17 ships and around 300 crew, including the British-owned cargo ship Ariana, hijacked overnight with its Ukrainian crew. The attack on the Ariana, about 1,000 miles (1600 kilometers) from the sea corridor NATO guards and the seizure of explosives from the group that attacked the crude oil tanker MV Kition may indicate the pirates are adapting their tactics as crews become better trained in counter-piracy measures. Sailors are aware that pirates generally attack during the day and that some guidelines suggest designating a safe room with a bulletproof door where crews can lock themselves in case of an attack. Such a room would still be vulnerable to being blown open with explosives. It was the first time NATO forces found pirates armed with raw explosives, Lt. Cmdr. Fernandes said from the Portuguese frigate the Corte-Real, which responded to the attack. The Corte-Real had sent a helicopter to investigate a distress call from the Greek-owned and Bahamian-flagged Kition late Friday about 100 miles (161 kilometers) north from the Somali coast in the Gulf of Aden.