Two more ships taken hostage and two fired on with rockets
Somali pirates hijacked two more cargo vessels and opened fire on two others on Tuesday.
They captured the Greek-owned MV Irene EM and Togo-flagged MV Sea Horse.
The pirates attacked at night, which is unusual, using the moonlight to see.
Another pirate gang fired automatic rifles and rocket-propelled grenades at the Liberian-flagged 21,887-tonne Safmarine Asia. It managed to escape and that there was no word of any casualties.
The US-flagged cargo ship Liberty Sun also was attacked by pirates firing rocket-propelled grenades and automatic weapons, the ship's owner, New York-based Liberty Maritime Corp, said in a statement.
The pirates damaged the ship but did not manage to board it. Liberty Sun immediately requested help from the US Navy and is now under escort. The ship was carrying US food aid and headed to Mombasa, Kenya, from Houston.