The most serious injury appeared to be to Tampa winger Simon Gagne, who fell awkwardly to the ice after being checked into the end boards by Washington defenseman Scott Hannan after Gagne had played just 2:34.
Gagne, who has a history of concussions, fell on his left shoulder, and his head banged against the ice.
A stretcher was immediately brought onto the ice, but Gagne eventually got to his feet with the help of Tampa training staff and was assisted off.
Hannan spoke briefly to Gagne as he headed off the ice. No penalty was called on the play, and Gagne was taken back to the team hotel.
"It's scary. You never want to see a guy on any team, never mind a guy on your own team, go down like that. As he was going off, he said he was OK. That was reassuring. It was a tough play. No one really saw it," teammate Steven Stamkos said. "He said he was OK coming off the ice. That was definitely a positive."
"You obviously don't want to imagine the worst," Lightning coach Guy Boucher added.
"But at the same time, I'll be honest, I think our entire staff and our organization, we care about our players. For us, they're not numbers, they're people, and the first thing that comes to mind is not I've lost a player but I hope his health is OK and there's nothing dangerous. And obviously when you see the stretcher coming out, it's not exactly what you want to see. Knowing that he's fine at the hotel, I guess, and we'll see tomorrow, it's at least a lot better of an outcome than it was looking like when he was on the ice for sure," Boucher said.
The Lightning also lost defenseman Pavel Kubina, who was hit by Jason Chimera late in the second period. Chimera was penalized for roughing as Kubina's head hit the glass as Chimera finished his check. The Lightning scored the winning goal on the ensuing power play, but Kubina did not return to the ice after the hit.
"They're back at the hotel now. They're going to be re-evaluated tomorrow, and we'll see where we go from there. That's the extent of what I know," Boucher said of his players.
Carlson did skate onto the ice to start the third period but skated just a couple of shifts.
"I mean, he's day-to-day. I'm hoping he can go Sunday. But at the same time, when you lose John, you lose pretty well half of your, really, your offensive defensemen," coach Bruce Boudreau said.