Police have not determined a motive for why Darion Marcus Aguilar, 19, fired fatal gunshots in a Maryland mall Saturday, but they found a journal in which Aguilar expressed "general unhappiness with his life," Howard County Police Chief Bill McMahon said Sunday.
Aguilar, who lived in College Park, Md., fatally shot two people who worked at The Mall in Columbia before killing himself.
Read: Maryland Mall Shooter ID'd
Police were still trying to determine whether Aguilar knew either of the victims, Brianna Benlolo, 21, of College Park, and Tyler Johnson, 25, of Mount Airy. They were killed at Zumiez, the apparel store where they worked.
Benlolo also lived in College Park, but police have not learned whether she and Aguilar knew each other.
As of Sunday evening, police had not found any relationship between the shooter and his victims, McMahon said at a news conference.
Police said Aguilar used a Mossberg 12-gauge shotgun that he bought legally in December. They believe Aguilar died from a self-inflicted gunshot wound. The shotgun was found near his body.
He arrived at the mall by cab around 10:15 a.m. Saturday. Reports of shots came an hour later.
Aguilar carried a backpack containing homemade explosive devices. He also had a great deal of ammunition, McMahon said.
Another victim was shot in the foot. She told police she was on the lower level of the mall. Police believe Aguilar fired between six and nine shots inside and outside the Zumiez store, which is on the mall's upper level, and at least one of those shots hit the lower level. Police did not release that victim's name.
Four other people suffered minor injuries from medical conditions or from falling in the rush to get away, police said.
Lauryn Stapleton, 18, who works at the Cartoon Cuts hair salon for children on the mall's second floor, said she witnessed the shooting near an escalator. She was getting food for her boss at McDonald's, downstairs in the food court, when she heard a loud sound from the level above.
"It sounded like somebody had dropped a brick off the top ledge and I heard someone say, 'Shots fired.' So I grabbed a kid and I looked. Three people fell to the ground. I grabbed the kid and ran, had the mother follow me," Stapleton said.
Tarah Lancaster-Williams and Tonya Broughton were at a spa for a "ladies' day out" when they saw people running.
"There was panic," Broughton said, flecks of the cream from her facial still on her face. "I mean, if you can imagine just hearing those words, 'There's a shooter.' No one really thinks twice when they hear those words. You really start to flee. So we fled to the nearest store - and even in there you didn't know if someone was coming in there."
Broughton said the two, who had been sitting next to each other in the salon, lost track of each other.
"As much as you think you've seen this on the news forever and you think, 'Here's what I'm going to do, I'm going to go this way,' that all goes out the window," Broughton said.
They both ended up in the mall's Victoria's Secret store, where Broughton said managers locked store gates. "They were extremely comforting and kept us updated," she said. "They were calm, and we just hugged each other and tried to talk to each other."
Ed Main was shopping at the Justice store with son Noah, 15, daughter Tori, 12, and niece Ana Collins, 18, when they heard two loud pops. He said they were hustled by an employee into a storeroom in the back of the store. Main, from nearby Westminster, said the employee "shut the door and barricaded it from the inside."
It was more than an hour before they were able to leave the mall.
After the shooting, the Mall in Columbia sent out this statement on its Twitter feed: "Our hearts & prayers are with everyone in the Columbia community."
Zumiez posted a statement on Facebook from CEO Rick Brooks that said, "We're working with the Howard County police department and all information will come through them." It said "the Zumiez team is a tight-knit community and all of our hearts go out to Brianna and Tyler's families."
The mall was expected to reopen at 1 p.m. Monday. There will be a "strong police presence," McMahon said.