Walker, a 2015 fourth-round pick, is at the Jackson Memorial Hospital in Miami.
“Oh my God,” Head Coach John Harbaugh said. “This is devastating news. Our prayers and hopes are with Tray and his family tonight.”
Walker, 23, attended Miami Northwestern High School and played his college football at small-school Texas Southern.
The 6-foot-2, 199-pounder was a developmental player for the Ravens last season. Walker played in eight games and recorded one solo tackle from scrimmage. He mostly competed on special teams.