In the aftermath of the shootings that left three dead at The Mall in Columbia, federal, state and local agencies have mobilized to support the Howard County Police Department in its investigation.
At approximately 11:15 a.m. Saturday, Howard County's 911 dispatch center received more than 40 calls from the mall. Police arrived on the scene within two minutes, Howard County Executive Ken Ulman said. The Howard County Department of Fire & Rescue Services also responded.
Anne Arundel County police provided assistance as well in the form of SWAT and patrol officers to ensure community safety.
Police found the bodies of Brianna Benlolo, 21, of College Park, and Tyler Johnson, 25, of Mount Airy, inside the Zumiez store in the mall. Nearby, the body of the man identified as the gunman, Darion Marcus Aguilar, 19, of College Park, was also found.
Five citizens were taken to Howard County General Hospital for injuries that were not life-threatening; they were treated and released by 5:15 p.m., according to the hospital.
Two Maryland State Police helicopters flew in, according to agency spokesman Greg Shipley.A bomb robot from the Office of the State Fire Marshal arrived, along with its expert bomb technicians, Shipley said.
According to Howard County police, Aguilar had crudely made explosive devices in a bag in the store.
The area was "an incredibly large crime scene," Howard County Executive Ken Ulman said.
Tactical troopers and K-9 units helped with the ensuing search of the mall, Shipley said.
Prince George's and Montgomery counties sent officers to assist, and Howard County police patrolled the mall's perimeter overnight with assistance from state troopers.
As Howard County police were investigating the crime scene on Saturday afternoon, the mother of the shooter called 911 in College Park, according to a statement from the Prince George’s Police Department.
She filed a missing person’s report with the Prince George’s County Police Department at approximately 1:40 p.m. when her son did not show up for work at Dunkin' Donuts in College Park, according to WBAL.
Aguilar was scheduled to work at a Dunkin Donuts shop near Route 1 and Cherry Hill Road in College Park early Saturday morning, The Washington Post reported.
Once someone reports a missing person in Prince George’s County, the case is assigned to an investigator and "should evidence and/or suspicious circumstances indicate, the case may be escalated to a higher priority," Lt. William Alexander of the Prince George's Police Department said.
An investigator went to the Aguilars' College Park home in the 4700 block of Hollywood Road at approximately 5 p.m. Saturday, according to a statement from the Prince George’s Police Department.
On his visit, the investigator saw a journal that belonged to the missing man, and "the portion of the journal that he read made him concerned for the missing person's safety,” according to a statement from Prince George’s police.
“The investigator began to actively search for the missing man,” the statement said. He tracked Aguilar’s phone and "soon determined it was pinging at the Mall in Columbia,” police said.
The investigator arrived at the mall before 6 p.m. and turned the missing person information over to the Howard County Police Department, which was handling the crime scene.
“Not long thereafter, it was confirmed the missing person and the deceased gunman were one and the same," Prince George's police said.When police tried to establish a motive in the mall shootings, they ended up back at the Aguilars' home in College Park.
The Prince George's County Fire Department Bomb Squad cleared the way for police from Howard County and agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) to enter. There, authorities seized a journal in which the teen expressed he was "unhappy with life," according to police.
Police also found ammunition, NBC News reported.
In December, Aguilar made two visits to the United Gun Shop in Rockville, where he purchased the Mossberg 12-gauge shotgun and ammunition, police reported Monday.
ATF agents called United Gun Shop and asked the owner at approximately 3 p.m. Saturday about the sale of the gun, according to WJLA, which reported the shooter told the store owners his gun was for home protection.
The store owner described Aguilar as polite and said there were "no red flags," WJLA reported.
Howard County police said Monday that as additional information from employees and the public comes in, officials are investigating.
Police said that the department would provide additional presence, in conjunction with mall security, at The Mall in Columbia for the next week.