WASHINGTON (Reuters) - Pirates attacked a U.S.-flagged cargo ship off the coast of Somalia with rockets and automatic weapons, but failed to board the craft, the ship’s owner said on Tuesday.

Greek-owned MV Irene E.M carrier is seen in an undated photo. REUTERS/Roberto Smera/Handout

The crew of the Liberty Sun was unharmed, but the vessel suffered damage, according to a statement from Liberty Maritime Corp of Lake Success, New York.

The ship immediately requested help from the U.S. Navy and was now under escort, the statement said.

“We are grateful and pleased that no one was injured and the crew and the ship are safe,” it said.

Liberty Maritime said the pirates fired rocket-propelled grenades and automatic weapons at the vessel, which was carrying U.S. food aid for African nations and was en route to Mombasa, Kenya, from Houston, it said.

A spokesman for U.S. Central Command had no immediate comment on the incident.

It was the second attack in a week on a U.S.-flagged ship in the region. On Sunday, U.S. snipers killed three Somali pirates and freed the American ship captain they had been holding hostage for five days.

Heavily armed pirates from lawless Somalia have been increasingly striking the busy Indian Ocean shipping lanes and strategic Gulf of Aden, capturing dozens of vessels, hundreds of hostages and making off with millions of dollars in ransoms.

Earlier on Tuesday, Somali pirates hijacked two more cargo vessels and opened fire on a third in attacks that showed a determination to go on striking at shipping on the region’s strategic trade routes.

The attacks were a clear sign pirate gangs have not been deterred by two raids in recent days in which U.S. and French special forces killed five pirates.