The injury seemed to have occurred at some point during the second period. The Rangers were lining up for a defensive zone faceoff when Zibanejad doubled over, leaning on his stick across his legs. This itself is common for forwards to do before a faceoff, only he never got out of the position. Eventually, Rangers defenseman K'Andre Miller went over to check on him and he still appeared to be in distress, even getting the attention of one of the referees.
After a short pause, Zibanejad slowly skated back to the Rangers bench with the help of his teammates. He immediately went down the tunnel towards the locker room and it did not look good.
As he was going off, the Rangers veteran appeared to be holding his abdomen, possibly indicating that he is dealing with some kind of stomach bug as it is not a common area to get injured in a hockey game. However, we do know that players often play through illness. Perhaps he is dealing with the flu?
UPDATE
Zibanejad returned to the Rangers bench several minutes later, missing less than 5 minutes of game time in total. We will just have to wait for more information about this situation from Zibanejad himself as well as head coach Peter Laviolette after the game.
It would seem that whatever was bothering him was not that serious given how little time he missed. Hopefully for Rangers fans this is in fact the case, as Zibanejad remains one of the team's most important players. He is currently tied for second on the team in scoring with 2 goals and 9 assists for 11 points through 13 games. If he does end up missing a game as a result of this, it would be a big void in the lineup to fill.