Egypt has arrested three people who opened fire with machine guns on a ship passing through the Suez Canal, an army source said on Sunday, playing down what the waterway's chief described as a terrorist attack.During Saturday's unsuccessful attack, the Panamanian-registered container ship COSCO ASIA came under fire in a northern section of the canal, a major global trade artery which is secured by the Egyptian armed forces."There was an attempt to disrupt security in an area called el-Qantara as they fired at a ship in an attempt to halt [traffic on] the waterway," said the army source.