NBC reports:

At least three people were killed Saturday in a shooting at a shopping mall in Columbia, Md., near Baltimore on Saturday, police said.
“Three people confirmed dead at Columbia Mall. Victims unknown at this time,” Howard County Police wrote in a tweet on Saturday.
In separate posts on Twitter, police added that one of the victims was located near a gun and ammunition and later wrote, “One of the dead subjects is the suspected shooter.”

...Three witnesses told NBCWashington.com that the gun used in the shooting was a shotgun, though police have not yet confirmed that.

A comment to this report:

Give us back our 2nd amendment rights and you wouldnt have this happening. Has anyone thought of investigating the CIA regarding these attacks? They perfected the manchurian candidate 40 years ago. Members of the CIA as well as their psychiatrist that brainwashed Sirhan Sirhan have already come forward on tape and told their stories.