Patterson said she moved to Columbia from Baltimore three years ago because she thought it was a safe place to raise her family.
"To me it was an escape from all the drama, a little paradise," she said.
Many customers inside the mall were directed toward the AMC Theater, away from the scene of the shooting. Some were loaded onto buses.
Heavy police presence remained at the mall into the night, with helicopters circling overhead and police officers searching car trunks in the parking lot.
Zumiez CEO Rick Brooks said in a statement that the company is making arrangements for counseling for their employees in the area.
"We are deeply saddened by the violence that has occurred this morning within our store in Maryland at The Mall in Columbia. Our hearts go out to the victims and their families," Brooks' statement said. "The Zumiez team is a tight knit community and all of our hearts go out to Brianna and Tyler's families."
Officials including Gov. Martin O'Malley and Rep. Elijah E. Cummings, expressed their condolences and commended the first responders.
"While we do not yet have full details of what has happened, my thoughts and prayers are with the families of the victims, and those injured in the shooting," Cummings said in a prepared statement. "I commend the work of law enforcement officers and first responders currently on the scene for their quick and highly professional work in securing the mall and getting people to safety."
Baltimore Sun reporters Justin Fenton, Eduardo A. Encina, Carrie Wells and Alison Knezevich contributed to this article.