Peek was responding to a report of a domestic assault in the 800 block of Frost Valley Lane on Friday afternoon when he became involved in a "physical altercation" with resident Gary Petrie, police said. They said Peek was "in fear for his life" when he shot Petrie in the upper body.
A woman from the residence was taken to the Baltimore Washington Medical Center in Glen Burnie to be treated for non-life-threatening injuries.
Police said Monday that Peek appears to have used "a progression of non-lethal department-issued weapons" to subdue Petrie. At some point, police said, Petrie "obtained an object to be used as a blunt force object."
Peek, "fearing that he was in immediate danger of serious personal injury," fired his department-issued handgun at Petrie.
The incident remains under investigation.