The Sabres (6-22-4) played without coach Don Granato and assistant Matt Ellis, who were unavailable due to NHL COVID-19 protocol. General manager Kevyn Adams filled in for Granato.
"It's terrible to lose in any way," Adams said. "Suite level, press box, ice level. Player, coach. It doesn't matter. It's tough. It wears on you. You want better. What I said to the guys after the game is we're all in it. We're in it together."
Dustin Tokarski made 27 saves for Buffalo, which is 0-14-2 since Feb. 25 and extended the NHL shootout-era record for most consecutive losses. The shootout was implemented in the 2005-06 season, eliminating ties.
Buffalo's stretch without a win is the longest in the NHL since Pittsburgh lost 18 in a row from Jan. 13-Feb. 22, 2004.
"In a season of unfortunate and terrible events, we're just ready for it," Sabres forward Taylor Hall said. "We had a lot of good stuff going on. What we're going through, it's got to be the toughest stretch for anyone on our team, that they've ever gone through. It's hard."
Radim Zohorna, making his NHL debut, gave the Penguins a 1-0 lead at 17:21 of the first period on his first shot. Anthony Angello made a backhand pass to the left face-off circle, setting up Zohorna for a one-timer to the glove side.
McCann scored with a wrist shot from the slot on the power play to make it 2-0 at 1:27 of the second period, then extended the lead to 3-0 with another wrist shot on the power play at 8:56 of the third.
"Jared can score goals. We've said that for a while now," Penguins coach Mike Sullivan said. "He can really shoot the puck. He's got a really deceptive release and he shoots it hard. I think with this particular time with the injuries that we have, we're relying on him to help us offensively. We think that's a strength he has."