(CNN) -- The gunman who killed two workers Saturday at a Maryland mall was identified Sunday as Darion Marcus Aguilar, Howard County Police Chief Bill McMahon said.
Aguilar arrived by cab about an hour before the shootings, and his movements at the mall were limited, McMahon said. He added that Aguilar, 19, fired between six and eight shots from a 12-gauge shotgun. That included a self-inflicted fatal shot.
On Saturday, police said the gunman carried "a large amount of ammunition" and apparent makeshift explosives. He killed 21-year-old Brianna Benlolo and 25-year-old Tyler Johnson at the busy Columbia mall before turning the shotgun on himself, police said.
Aguilar purchased the gun, made by Mossberg, in December, the chief said Sunday at a morning update for reporters.
The shootings, which also left five others injured, ended a violent week which saw shootings or gun scares at American schools or shopping centers -- ordinary places where people once felt safe.
McMahon told reporters that the shooter's motive was unclear. He said authorities were investigating whether Aguilar knew either of the victims.
Both worked at Zumiez, a shop that caters to skaters, on the second floor of The Mall in Columbia.
Benlolo was an assistant manager at the store and had worked there since November 2012, according to her Facebook page.
Johnson had worked at the store for about three months, according to his Facebook page.
The body of the suspected shooter was found near a shotgun on the floor of Zumiez, police said, along with unspent ammunition.
Late Saturday, police revealed that "two crude devices that appeared to be an attempt at making explosives using fireworks" were found inside the shooter's bag inside the store. "Both were disabled," police added.
Thousands in mall at time of shooting
The first 911 call about the shooting came at about 11:15 a.m. and officers were in the mall within two minutes, police said.
The shooting "seems to have been very contained to that store and the area just outside," McMahon told reporters.
Police entered the mall within minutes of the first 911 calls and found three people dead. The scene was secure shortly before 1 p.m., police said.
Investigators said there were thousands of people in the mall at the time, with many hiding in fear behind store counters, in restrooms or in fitting rooms for hours after the shooting stopped.
"Think about this, on a Saturday afternoon at the mall, how many people may be in there," McMahon said. "Something like this happens and people run in many directions, and they also do what we train them to do -- to shelter in place."
Five people were transported to Howard County General Hospital, a hospital spokeswoman said in a statement. All were treated and later released.
Four of them suffered injuries related to the chaotic scene after the shots rang out, including one with a seizure and at least one with a sprained ankle, according to McMahon.
The other injured victim suffered a gunshot wound to the foot. Police said Saturday night that that woman wasn't in Zumiez; rather she was on the first floor when she was struck.
A federal official briefed on the shooting told CNN that preliminary information indicates the shooting may have been related to a domestic dispute.
McMahon said Sunday that police had yet to determine that but learned Saturday night that one of the victims lived near the shooter.
Worker at mall: 'It was just crazy'
The gunfire sent shoppers and workers running for cover, witnesses told CNN.
"It's a mall shooting," one mall worker, identified only as K.T., told CNN. "No one knows what's going on. In today's world, you hear gunshots and you run."
The staccato of gunfire was followed by the cries and screams of children and adults running or ducking for cover, the employee said.
"A lot of kids were crying, and mothers were holding onto them," K.T. said. "I wasn't worried about me. I was just making sure everybody was OK."
Once the shooting stopped, SWAT team members moved from store to store.
"It was just crazy," said K.T., who snapped a picture of a bullet-riddled wall near the shooting scene. "It's one of those things you see on TV but never expect you'll go through."
Colin Ready, another employee, said he heard a couple of booms and thought the sounds were from construction. Then, there were several more booms and people were screaming and scattering, he said.
The manager of the store where Ready works closed the front gate, he said. When a police officer, not in uniform, came to the gate later to say the mall had been secured, Ready said workers didn't believe he was a cop.
Laura McKindles, another mall employee, told CNN affiliate WJLA that she heard eight to 10 gunshots.
"I have never experienced anything like this in my life," she said. "I was standing there talking to a customer and I started hearing all this banging coming from the food court ... and people started running. And they said somebody's down there and they got a gun."
Near tears, she added: "This country needs a lot of help. When somebody is that angry to go to a mall on a Saturday morning and shoot people, we're in a lot of trouble. ... To push people to those limits where things like that happen makes no sense."
Images on Twitter reportedly from the scene showed mall employees and customers hiding in a stockroom. The mall was on lockdown for some time.
In the moments after the shooting, the fire department, via Twitter, advised people to avoid the area.
"I'm terrified," said Lauryn Stapleton, a mall employee who barricaded herself in a room for an hour and half after the shooting."It's just something I never want to experience again. I'll go back to work but it will be hard."
Several university shootings earlier last week
The Mall in Columbia released a statement hours after the shooting, announcing it would remain closed for the remainder of Saturday. Police said later that the mall would be shuttered Sunday as well, while K-9 units continued checking the mall "through the night" to make sure all was safe.
"We are deeply saddened by the violence that has occurred this morning within our store in Maryland at The Mall in Columbia," Zumiez CEO Rick Brooks said. "We're making arrangements for counseling to be made available to Zumiez employees in the area."
The mall shooting was the latest instance last week of gun violence or threats of it 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.
On Monday, a student was shot and critically injured near a gym at Widener University near Philadelphia. Police were looking for a suspect.