Updated

Somali pirates fired grenades and automatic weapons at an American freighter loaded with food aid but the ship managed to escape the attack and was heading Wednesday to Kenya under U.S. Navy guard, officials said.

Despite President Barack Obama's vow to halt their banditry and the deaths of five pirates in recent French and U.S. hostage rescue missions, brigands seized four vessels and more than 75 hostages off the Horn of Africa since Sunday's dramatic rescue of an American freighter captain.

That brought the total number of sailors being held by Somali pirates to over 300 on 17 different ships — a distinct surge in the number of captives over the last few days.

Pirates can extort $1 million or more for each ship and crew — and Kenya estimates they raked in $150 million last year.

The Liberty Sun's American crew was not injured in the latest attack but the vessel sustained some damage, owner Liberty Maritime Corp. said.

Still, the attack foiled the reunion between the American sea captain rescued by Navy snipers and the 19-man crew of the Maersk Alabama who he had saved with his heroism.

Capt. Richard Phillips was planning to meet his crew in the Kenyan port of Mombasa and fly home with them Wednesday. But Phillips was on the USS Bainbridge when it was diverted to help the Liberty Sun, and the crew left Mombasa without him Wednesday on a chartered plane.

"We are very happy to be going home," crewman William Rios of New York City said before departing. "(But) we are disappointed to not be reuniting with the captain in Mombasa. He is a very brave man."

Maersk spokesman Gordan van Hook said crew members would arrive late Wednesday at Andrews Air Force base in Maryland. Their reunion with Phillips will now take place in the United States, he said, without elaborating.

Liberty Sun sailors used one of the same tactics Phillips employed to foil the pirates — blockading themselves inside the engine room.

"We are under attack by pirates, we are being hit by rockets. Also bullets," crewman Thomas Urbik, 26, wrote his mother in an e-mail Tuesday. "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."

The Liberty Sun "conducted evasive maneuvers" to ward off the pirates, said U.S. Navy Lt. Nathan Christensen, spokesman for the Bahrain-based 5th Fleet.

"That could be anything from zigzagging to speeding up to all kinds of things," he said. "We've seen in the past that that can be very effective in deterring a pirate attack."

The USS Bainbridge responded to the Liberty Sun's call for help but the pirates had left by the time it arrived five hours later, Navy Capt. Jack Hanzlik said.

A small detachment of armed U.S. sailors are now on the Liberty Sun as it continued its journey to Mombasa. The ship, with 20 American mariners, had left Houston with a load of humanitarian food aid for the U.N. World Food Program. Some of that aid was destined for Somalia, where nearly half the country's 7 million people depend on food aid.

This year, Somali pirates have attacked 79 ships and hijacked 19 of them. One pirate declared they are grabbing more ships and hostages now to prove they are not intimidated by Obama's pledge.

"Our latest hijackings are meant to show that no one can deter us from protecting our waters from the enemy because we believe in dying for our land," Omar Dahir Idle told The Associated Press by telephone from the Somali port of Harardhere.

U.N. spokesman Peter Smerdon said more food aid was to have been delivered by another cargo ship hijacked by pirates on Tuesday, the Lebanese-owned MV Sea Horse. It was headed to Mumbai, India, to pick up 7,327 tons of WFP food for Somalia.

"WFP is also extremely concerned that people in Somalia will go hungry unless the Sea Horse is quickly released or a replacement ship can be found," Smerdon said.

Pirates say they are fighting illegal fishing and dumping of toxic waste in Somali waters but now operate hundreds of miles from there in a sprawling 1.1 million square-mile danger zone.

A flotilla of warships from nearly a dozen countries has patrolled the Gulf of Aden and nearby Indian Ocean waters for months. They have halted many attacks but say the area is so vast they can't stop all hijackings.

The Gulf of Aden, which links the Suez Canal and the Red Sea to the Indian Ocean, is the shortest route from Asia to Europe and one of the world's busiest shipping lanes.

In an unusual nighttime raid, pirates seized the Greek-managed bulk carrier MV Irene E.M. before dawn Tuesday, with at least 21 crew. Hours later, they commandeered the MV Sea Horse carrying 19 crew. They also captured two Egyptian fishing trawlers carrying 36 fishermen.

Yemen's coast guard rescued 13 Yemeni hostages and their fishing trawler in a shootout Monday with pirates. No casualties were reported.

Meanwhile, three Somali pirates have been brought to the French city of Rennes to face an investigation, a French judicial official said Wednesday. They were arrested Friday in an operation to free the Tanit, a French ship seized in the Gulf of Aden.

Four French hostages were freed and one was killed, along with two pirates, in that raid.