NEW YORK (AP) – Somali pirates attacked and damaged an American ship carrying humanitarian aid Tuesday, but the ship and crew were safe under Navy escort, the military and shipping company said.

The pirates fired rocket-propelled grenades and automatic weapons at the Liberty Sun as it carried food for famine-wracked African nations, said the vessel’s owner, Liberty Maritime Corp. The ship was en route from Houston to Mombasa, Kenya, with a roughly 20-member crew, officials said.

“We are under attack by pirates, we are being hit by rockets. Also bullets,” crew member Thomas Urbik told his mother by e-mail. “We are barricaded in the engine room and so far no one is hurt. (A) rocket penetrated the bulkhead but the hole is small. Small fire, too, but put out.”

After the ship reported being attacked around 11:30 a.m. EDT, the USS Bainbridge – the destroyer that assisted in the rescue of the hijacked Maersk Alabama last week – sailed to its aid, said Navy Capt. Jack Hanzlik, a spokesman for U.S. Central Command in Tampa, Fla.

The Bainbridge arrived at 5:30 p.m. EDT to find that the pirates had left, and there were no injuries, Hanzlik said.

The ship was continuing on its way to Mombasa late Tuesday, he said.

The vessel had delivered thousands of tons of American food aid earlier this week in Port Sudan, in nearby Sudan, earlier this week, Lake Success, N.Y.-based Liberty Maritime said in a statement.

It was carrying rice, cooking oil, plywood and other supplies, said Urbik’s mother, Katy Urbik of Wheaton, Ill.

Her 26-year-old son had been e-mailing her updates on the voyage every 36 to 48 hours. A member of the Marine Engineer Benefit Union who lives in Batavia, Ill., he had been working on the ship since Feb. 13.

She was nervous as he told her Sunday the vessel was heading into pirate-patrolled waters, but somewhat relieved when he told her early Tuesday the crew was reporting its position to the Navy every six hours.

“I’m thinking, ‘If the Navy’s monitoring him, and they have all these preparations made, I think they’re going to make it,”‘ she recalled in an interview.

Then came another message: “The one that stopped my heart – that said, ‘We’re under attack,”‘ she said.

But then there was a follow-up e-mail “that said he was safe and they had a Naval escort taking them in,” she said.

Urbik said she was “very relieved and grateful to God for protecting him and to our Navy, and that we come from a country that can respond like that and protect our citizens.”

Liberty Maritime also praised the government’s response, as well as that of it crew.

“We commend the entire crew for its professionalism and poise under fire,” the company said. President Philip J. Shapiro and chief financial officer Dale B. Moses declined to comment beyond the written statement.

Founded in 1988, Liberty Maritime has delivered more than 28 million tons of U.S. food aid to more than 40 countries, according to its Web site.

President Barack Obama vowed Monday to “halt the rise of piracy,” but defiant Somali pirates seized a total of four more ships with 60 hostages Tuesday.

The pirates have vowed vengeance for five colleagues slain by U.S. and French forces in two hostage rescues since Friday. The pirates say they are fighting illegal fishing and dumping of toxic waste in Somali waters but have come to operate hundreds of miles away in a sprawling 1.1 million square-mile danger zone.