Transcript for Columbia, Maryland Mall Shooting Gunman Details Revealed
We move on to chilling new details of the murders at mall in Maryland this weekend. Still unclear why a teenager opened fire killing two other young people before turning the gun of himself. This morning, we're learned more from the gunman's stunned and sad mother. Reporter: Overnight rkts police are poring over a journal seized from this house. Where Darion Aguilar lived with his mother. It could hold clues. There is a journal. He does express some general unhappy ps with his life. Reporter: 19 years old and out of school less than a year, he walked into a skateboarding shot and fired six to eight shots. He killed two and caused terror for hundreds. Kids are hiding in the bathroom in the upper level near the sears, hearing active shots. Reporter: His victims, Tyler Johnson, 25, and Brianna benlolo, a single mother. Her instagram account reads live every day for today. Darion is a good kid. Don't know what happened. Reporter: We visited his home. His mother didn't answer the door but spoke briefly by telephone. She sobbed telling ABC news her son was gentle and never had interest in guns. But police say he did. He bought a shotgun last month. A 12-gauge mossburg and kept it hidden as a cab dropped him off at the mall. A surveillance tape showed him sitting and walking around for nearly an hour. The gunfire lasted only moments but sparked an afternoon of chaos. As the mall reopens today, fresh worry. I don't brink my kids to malls. I have four little ones. I can't save them all. Reporter: For "Good morning America," Jeff Zeleny. And to the cruise ship
This transcript has been automatically generated and may not be 100% accurate.