Update, 1/26: 6:28 a.m., ET: The gunman has been identified as 19-year-old Darion Marcus Aguilar, according to Howard County Police Chief Bill McMahon.
Aguilar arrived at the mall in a cab and fired between six to eight shots.
Police also revealed that Aguilar was carrying "two crude devices that appeared to be an attempt at making explosives using fireworks" inside his bag, according to CNN.
The Howard County Police released a picture of the suspected shooter on twitter.
Update, 5:57 p.m., ET: Police have identified the two victims in the shooting at the mall in Columbia, Md.
The two victims, both employees at Zumiez, have been identified by police as Brianna Benlolo, 21, of College Park, Md., and Tyler Johnson, 25, of Ellicott City, Md.
Chief McMahon told reporters that after shooting the two employees. the shooter killed himself, CNN reported. There is not yet a clear motive, but the shooter was found with a large amount of ammunition.
Brianna Benlolo is listed as an assistant manager at Zumiez on her Facebook page.
Update, 4:20 p.m., ET: McMahon said the two victims worked at a shop in the mall.
The two victims are an adult male and an adult female in their 20s who worked at a store in the mall, Chief Bill McMahon said in a second press conference. Police don't yet know the identity of the shooter or have a motive.
The shooter's body was also said to have been found outside a Zumiez store.
Update, 2:42 p.m., ET: Four people from the mall who were injured were brought to the hospital, a Howard County General Hospital spokeswoman said in a statement.
Of the four injured, one was a shooting victim, one had a seizure and another had a sprained ankle. All four were reportedly in good condition.
Update, 1:41 p.m., ET: McMahon confirmed in a press conference that one of the victims appears to be the shooter and they believe that person acted alone, but said they have not yet identified the deceased.
McMahon confirmed the shooting took place on the upper level of the mall, and that they are "very confident" the shooter acted alone.
"We do not think at this point that there are any other shooters in or around the mall," he said.
McMahon added that they believe people may still be hiding inside the mall and that a SWAT team was seeking them out.
"Think about this, on a Saturday afternoon at the mall, how many people may be in there," he 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."
Howard County Executive Ken Ulman also spoke, saying that the crime scene was "still active" and "is going to be an active crime for some time."
At least three people were killed in an afternoon shooting at Maryland's Columbia Mall, the official Twitter account for the Howard County Police Department confirmed. One of the dead is the alleged gunman.
"Swat team moving into Columbia Mall. #activeshooting #mall #columbiamall #shooting"
The shooter was reported to be on the second floor of the massive mall in Maryland's Howard County, according to CNN.
As of 12:30 p.m. ET, the incident appeared to be over.
The shooting first occurred around 11 a.m., according to the Howard County police account.
Check back for updates.