Ranger was taken off the ice on a stretcher late in the first period after being injured on a hit from behind. He was stable, conscious and alert at the hospital.
Ranger was boarded by Lightning forward Alex Killorn with 4.1 seconds remaining in the period. Ranger was motionless face down on the ice before being tended to by Maple Leafs trainers and medical personnel. His head was secured by a brace and he could be seen moving his legs while down.
Ranger and Killorn were pursuing the puck behind the goal line when they collided, with Ranger's head hitting the glass.
"It's one of those textbook hitting from behind. That's what it looked like," Maple Leafs coach Randy Carlyle said. "But I didn't really get a look if he turned into him or if the puck bobbled in his feet or any of that; I didn't really get a look to that. I was just more interested in seeing the well-being of the player, and that was it."
Killorn was given a five-minute major for boarding and a game misconduct.
"Pretty unfortunate," Killorn said. "Happy that he is OK, I heard through the PR and stuff that he is doing all right now. It's kind of a scary moment, one of those plays where I commit to hit someone without knowing if they are going to turn, so it's just an unfortunate play."
With his Maple Leafs teammates and some Lightning players on the ice, Ranger was removed after a delay of about 10 minutes.
The first period was stopped at that point and played out immediately prior to the start of the second period.
Tampa Bay won, 5-3.