The pair of captains are anchoring the Terps' defense through their 3-0 start.
The Terps recorded their second clean sheet of the season but couldn't find a breakthrough against the Rams.
Karn replaces former coach Mark Montgomery, who resigned in July.
The former Tewaaraton Award winner and national champion joins the Terps’ staff after a stint in the NFL.
The Terps also picked up six field hockey commits, including two ranked in the top-10 nationally.
Through four games, Meghan Ryan Nemzer has leaned on the Terps' first-year players to play meaningful roles.
The Terps will face Towson for the first time in the head coach's tenure.
Locksley and Gattis teamed up at Alabama in 2018 as an offensive coordinator and co-offensive coordinator, respectively, and led the Crimson Tide to the national title game.
The Terps' coach has been experimenting with different combinations of attackers.
The Terps need to be more intentional about closing out games, per coach Meghan Ryan Nemzer.