(CNN) -- The mother of a 19-year-old accused of killing two people and himself at a Maryland mall told reporters that her son was a "gentle, sweet kid."
In the conversation, recorded Sunday by a reporter for radio station WNEW, the woman says Darion Aguilar never had a gun before and was a gentle teenager.
"If you were to go into his room you would see what a gentle, sweet kid he was," she says.
She says she cannot understand what happened and that she doesn't think her 19-year-old son knew the victims.
She adds that she feels for the parents of 21-year-old Brianna Benlolo and 25-year-old Tyler Johnson, who were shot dead with a shotgun on Saturday morning at the busy Columbia mall.
ABC also reported the mother's comments.
The woman's revelations come as police look into a journal written by Aguilar. The diary contains typical teenage writings about acne and rejection by girls, but nothing to indicate he was depressed, a family friend said Monday.
Family friend Ellis Cropper, who is serving as a spokesman for Aguilar's mother, told CNN on Monday that police reviewed the journal after the mother called police to file a missing person report.
Cropper said Aguilar's mother, with whom he was close, doesn't think he was dating anyone.
Police have said only that Aguilar's journal expressed "general unhappiness with his life."
According to police, Aguilar took a taxi to The Mall in Columbia on Saturday morning and then fired as many as nine shots from a Mossberg 500 shotgun into a skateboard apparel shop, killing Benlolo and Johnson before fatally shooting himself.
On Saturday, a federal official briefed on the shooting told CNN that preliminary information suggested the gunman aimed only at the two victims, perhaps indicating it was an isolated situation and not a wider shooting spree.
Police have offered no motive for the shooting.
"I know there's a lot of interest in the motive for this, and I have as much interest in that as anybody," Howard County Police Chief Bill McMahon said Sunday.
Aguilar was an avid skateboarder, Cropper said. As of now that's the only known link between him and the skate shop.
Prelude to the shooting
According to Cropper, here's what Aguilar's mother says happened before the shooting on Saturday:
Aguilar was scheduled to report to work for a 5:30 a.m. shift at Dunkin' Donuts, a job he had held since about September.
His mother offered to give him a ride to work, but he said he would get there on his own. Several hours later, she went to check on him, and the store manager said Aguilar had never showed up, according to Cropper.
The mother then called police to file a missing person report. When officers arrived at her home, she used a cell phone locating service to trace her son's phone.
It showed he was at the mall.
According to Cropper, police -- who were aware of the mall shooting -- then asked if Aguilar kept a journal.
Police later returned to the home and seized the journal, along with other potential evidence including computers and documents, according to McMahon, the police chief.
McMahon said Aguilar purchased the 12-gauge Mossberg shotgun in December and also had two homemade bombs in his backpack.
Benlolo was an assistant manager at Zumiez. She had worked there since November 2012, according to her Facebook page.
Her friend Evelyn McDonald said Benlolo, the mother of a small boy, was "just full of energy."
"She was so nice and just an amazing artist and just an amazing person inside and out," McDonald told CNN.
"She loved her son. She loved being a mother," McDonald said.
Johnson had worked at the store for about three months, according to his Facebook page.
Five people went to the hospital for treatment after the shooting. All were treated and released.
Four suffered injuries in the chaos after the shooting. The other injured victim suffered a gunshot wound to the foot. Police said the woman wasn't in Zumiez; rather, she was on the first floor when she was hit.
The mall reopened Monday afternoon, but the Zumiez store will be closed indefinitely, according to a sign on the boarded up storefront.
Memorial sites will be set up outside the mall and in the food court, officials said.
Gun shop owner recalls conversations with Aguilar
The co-owner of the United Gun Shop in Rockville confirmed Aguilar purchased a shotgun on December 10 for about $430 in cash.
Cory Brown, the co-owner, said Aguilar walked in with a friend and after spending about 30 minutes in the store, he was approved to purchase the Mossberg 500.
Brown said Aguilar seemed to know what he wanted.
"He came in and asked for something he can use for home defense. A platform he can start with and grow into. He asked a lot of good questions," Brown said.
Aguilar showed him a learners permit to drive and a change of address card. He filled out the ATF form and was approved within minutes.
Aguilar also purchased two boxes of ammo for a total of 32 shotgun shells, which each contained about 50 small pellets inside.
Brown said Aguilar came back just before Christmas with the same friend and purchased another box of shotgun shells.
He said he wanted to practice more with it, telling the gun shop owner, "there's more kick than I thought."
He purchased another box of shotgun shells for $16.
University shootings earlier last week
The shooting was the latest instance of gun violence or threats in ordinary places across the country.
A student was shot dead Friday afternoon at South Carolina State University, prompting a manhunt for several suspects that extended beyond the school's Orangeburg campus.
On Wednesday, the University of Oklahoma in Norman briefly shut down after a report of a possible shooting that apparently turned out to be a false alarm, the university's president said.
On Tuesday, a gunman shot and killed another student inside Purdue University's electrical engineering building. Police said Cody Cousins, 23, an engineering student, killed Andrew Boldt, 21, of West Bend, Wisconsin. Cousins was charged with murder.
Last Monday, a student was shot and critically injured near a gym at Widener University near Philadelphia. Police were looking for a suspect.
CNN's Ray Sanchez, Joe Sutton, Evan Perez, Greg Botelho, Adam Shivers and AnneClaire Stapleton contributed to this report.