Hedman played less than seven minutes in the first period, and Johnson played into the second period before leaving the game.
Lightning coach Jon Cooper said he doesn't know when the pair could return, but the team is prepared to play without them.
"[Johnson] is our leading scorer and [Hedman] is our leading scoring defenseman," Cooper said. "You pull any of those guys out of your lineup it's going to hurt. We'll see how we adapt. This happens to teams; it's happened to us before. We've been through it. You don't like to go through it but we have. And we'll respond."
Hedman, 24, has five goals and 15 assists this season for the Lightning. He is in his sixth season with the team since being the No. 2 pick in the 2009 draft.
The 24-year-old Johnson has 17 goals and 29 assists for a team-high 46 points this season. In his third year with Tampa Bay, he has nearly matched his career-high of 50 points that he set last season.
Tampa Bay has won seven of its last 10 games and leads the Eastern Conference with a 27-13-4 record.
The Lightning play at the Boston Bruins on Tuesday at 7 p.m. ET.
- Paul Palladino