A U.S. Navy nuclear-powered attack submarine collided with an unknown submerged object this weekend while traveling through international waters in the Pacific Ocean, according to the Navy.

The Navy describes the submarine as being in “safe and stable” condition and said it is making its way to port for a damage assessment that could help determine what it struck.

“The Seawolf-class fast-attack submarine USS Connecticut (SSN 22) struck an object while submerged on the afternoon of Oct. 2, while operating in international waters in the Indo-Pacific region,” said a statement from the Navy’s Pacific Fleet. “The safety of the crew remains the Navy’s top priority. There are no life threatening injuries.”

USNI News was first to report the incident involving the USS Connecticut.

Two sailors aboard the submarine were treated for what a Navy official described as “moderate injuries” and additional sailors received bumps, bruises and lacerations.

“The submarine remains in a safe and stable condition,” said the statement. “USS Connecticut’s nuclear propulsion plant and spaces were not affected and remain fully operational. The extent of damage to the remainder of the submarine is being assessed. The U.S. Navy has not requested assistance. The incident will be investigated.”

Officials said it remained unclear what the submarine struck while underwater. They said it could include stationary objects like a sea mount, an underwater sea mountain, or an object being towed by a surface vessel.

Two U.S .officials said the submarine is headed to the U.S. Naval Base Guam where a damage assessment of the submarine’s hull could help determine what the vessel struck underwater.