Transcript for Names and images of 7 deceased sailors released

Next tonight, the growing mystery after seven U.S. Sailors lost their lives. The question tonight, how did a massive container ship plow into U.S. Destroyer with sophisticated radar and warning systems and why were those U.S. Sailors put in such danger? Here's ABC's Matt Gutman with what we've learned tonight. Reporter: Tonight, the Navy investigating how a U.S. Destroyer with sophisticated radar and a crew trained to detect threats 24/7 could be so blind sided. The acx crystal slammed into the Fitzgerald's midsection at 1:32 A.M. Saturday, nearly an hour before the Navy says the collision occurred. Below the water line, the container ship's bow worked like a battering ram, t-boning two birthing compartments where more than 100 sailors slept. The Fitzgerald was taking on water. The crew of 300 knew sailors were missing but frantically worked to keep it afloat. They had to fight the ship to keep it above the surface, so, it was traumatic. Reporter: Helicopters medevaced the ship's captain, who was sleeping and knocked unconscious. Seven sailors would die, all found in the ship's sleeping quarters. They ranged in age from 19 to 37 from hometowns from Connecticut to California. Daryl martin lost his son, Xavier. It's very hard. My only child, all I have. Reporter: Is there a chance that the captain or the mates or other people on the ship could lose their jobs? Certainly. Absolutely. There's always that chance. Let's get to Matt Gutman with us live tonight. And we're learning there was a delay in reporting this collision? Reporter: That's right, David. It will certainly something that will be investigated. Seemed like a hit and run on the high seas, that cargo ship pl plowing through the Fitzgerald for 30 minutes before turning around. Only alerted authorities about the collision 50 minutes after it happened. David? Matt Gutman tonight, thank you.

This transcript has been automatically generated and may not be 100% accurate.