Walker, 23, was transported to Jackson Memorial Hospital in Miami in critical condition, the team said.
"This is devastating news," Ravens coach John Harbaugh said in a statement. "Our prayers and hopes are with Tray and his family tonight."
The Miami-Dade police department added further details in a press release.
"Walker was heading westbound on Northwest 75th Street on a Honda dirt bike with no lights and wearing dark clothing when he collided with a Ford Escape heading southbound on Northwest 21st Avenue at approximately 7:50 p.m.," the release stated.
NFL Media Insider Ian Rapoport reported Friday morning that Walker, who sustained severe head injuries in the crash, spent all night in surgery and is currently fighting for his life, per three sources informed of his condition.
A native of Miami, Walker attended Miami Northwestern High School.