Several sailors suffered minor injuries over the weekend after the fast-attack submarine USS Connecticut (SSN-22) collided with an underwater object in the Pacific.

The Connecticut, a Seawolf-class submarine out of Kitsap Naval Base in Bremerton, Washington, was underway in international waters when it “struck an object” the afternoon of Oct. 2, according to a statement from the U.S. Pacific Fleet. Although the Navy did not specify the location of the incident beyond the “Indo-Pacific region,” Sam LaGrone of U.S. Naval Institute News reported that it occurred in the South China Sea.

While it remains unclear what exactly the sub ran into, a Navy Times report said there were no indications the mishap was hostile or a collision with another vessel. A Navy official told Task & Purpose the hull was not breached and speculated that the boat may have run into a shipping container or an undersea mountain that was not on navigational charts. In 2005, the USS San Francisco ran into an uncharted mountain at top speed, killing one sailor and injuring 98 others.

“USS Connecticut’s nuclear propulsion plant and spaces were not affected and remain fully operational,” the Pacific Fleet statement said. Officials said the full extent of the damage was still being determined but the boat “remains in a safe and stable condition.” The service is investigating.

About 11 sailors reported injuries after the incident, according to Navy officials. Two suffered “moderate injuries” while others reported bumps, bruises, and lacerations that were treated by a corpsman on board. The boat, which is typically crewed by 101 enlisted sailors and 15 officers, is expected to pull into port in Guam to assess and repair any damage “imminently,” a Navy official said.

“The safety of the crew remains the Navy’s top priority,” the Pacific Fleet statement said. “There are no life-threatening injuries.”

Launched in 1997, the USS Connecticut is one of three Sea Wolf-class boats in active service. “Exceptionally quiet, fast, well-armed, and equipped with advanced sensors,” according to the Navy, the boats are larger than the Los Angeles-class at an overall length of 353 feet and can hold up to 50 weapons in its torpedo room.

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