Some fairly informed speculation in the forum comments here (”gCaptain” is a maritime related site): http://forum.gcaptain.com/t/uss-fitzgerald-collides-with-acx-crystal-off-coast-of-japan/45129/46
FWIW, Unconfirmed, from Reddit:
“I actually just got word from another shipmate that was on board the USS Fitzgerald as well. He said that the cargo ship did not appear on the radar and the lights were dim. They tried to turn, but by then it was too late. When they hit, the berthing rooms started to flood. They sealed off all the berthing rooms, essentially trapping the sailors because they thought no one was in any of the rooms to avoid sinking the ship.”