A Watertown man was among the seven Navy sailors killed in a collision off the coast of Japan this weekend.

Flags across the state are flying at half-staff in remembrance of Tan Huynh, a 25-year-old sonar technician aboard the USS Fitzgerald.

Divers found the sailors in the flooded compartments of the ship after they went missing following the crash with a container ship Saturday, authorities say. Two of the damaged compartments house the sleeping quarters for more than 100 crew members, many who were likely asleep.

Huynh's sister says he was selfless and often made other people smile.

She says her family is "blessed to have friends from all over being supportive and praying for us and feel even more blessed that Tan and the other six sailors fought for us and our country."

His sister says the family moved to Connecticut when he was in eighth grade. Huynh graduated from Watertown High School and took classes at Naugatuck Valley Community College before joining the Navy in 2014. The family has since moved out of state.

Sen. Richard Blumenthal said he was heartbroken to learn of Huynh's death and wants to know how this crash happened.

"The United States Navy owes the American people and this sailor's family a full explanation and a complete investigation and I'm going to press for it as a member of the Armed Services Committee," Blumenthal said.

Sen. Chris Murphy also issued a statement, saying Huynh died serving his country, a debt we cannot repay.

The Navy is launching an investigation into what caused the collision.