A U.S. Navy ship that once was used as a temporarily jail for suspected Somali pirates successfully evaded a pirate attack Wednesday off the Somali coast, a U.S. Navy official said Thursday.

The USNS Lewis and Clark, a Military Sealift Command ship normally used to transport cargo and ammunition, used to be configured to hold about a dozen pirates — and at one point held as many as 16 suspects.

On Wednesday, the ship "performed evasive maneuvers" and avoided being boarded by pirates on two skiffs that had pursued the ship for more than an hour, said Lt. Nathan Christensen, a spokesman with U.S. Naval Forces Central Command/5th Fleet.

The skiffs came within one nautical mile of the Lewis and Clark, officials said. At one point, the pirates fired small arms at the Lewis and Clark, though the rounds fell short of the vessel.

The ship was sailing north about 115 miles off of Somalia’s coast to provide supplies for U.S. Navy and coalition ships operating in the area. It was carrying primarily fuel, Christensen said, but it is also used to re-supply ships at sea with food, supplies and parts, and often delivers sailors’ mail.

An embarked U.S. military security crew did not fire any weapons at the skiffs, and used only a Long Range Acoustical Device, or LRAD, to issue verbal warnings, Christensen said.

The security team did not return fire because it is primarily there to provide "point defense" for the ship and crew, Christensen said.

There are about 130 civilian and military personnel on board. The vast majority were civilian mariners, he said.

As the skiffs drew nearer, the Lewis and Clark increased its speed and performed zigzag patterns to evade the attack.

"The actions taken by Lewis and Clark were exactly what the U.S. Navy has been recommending to prevent piracy attacks — for both commercial and military vessels," Capt. Steve Kelley, commander of Task Force 53, said in a Navy statement. "Merchant mariners can and should use Lewis and Clark’s actions as an unequivocal example of how to prevent a successful attack from occurring."

Until March, the Military Sealift Command ship had served as a staging platform for the U.S.-led Combined Task Force 151.

In February, 16 suspected pirates nabbed in separate incidents were detained on the Lewis and Clark until the Navy could transfer them to Kenya. In March, it no longer was needed to combat the piracy efforts, and reverted to its main mission as a cargo ship in support of military operations in the area, officials said.

Every year, more than 30,000 vessels transit the Gulf of Aden, recently dubbed "pirate alley." So far this year, there have been 97 attempted attacks on merchant vessels, 27 of which have been successful, officials said. As of Thursday, pirates continued to hold about 280 people held hostage from 17 ships, Christensen said.