BOSTON -- Wednesday night, the Buffalo Sabres spoiled a special night for the Bruins and their fans in the wake of Monday's Boston Marathon bombings, rallying for a 3-2 shootout victory.
Saturday, another day of tribute at TD Garden, and the visiting team again spoiled the celebration.
Jarome Iginla, playing his first game in Boston since spurning the Bruins in favor of going to Pittsburgh at the trade deadline, and Chris Letang scored third-period power play goals to give the Penguins their sixth straight victory, 3-2, and the Eastern Conference regular season championship.
The Penguins, who were playing without the injured Sidney Crosby, Evgeni Malkin and James Neal, earned home ice throughout the conference playoffs.
Pittsburgh still has a chance to catch Chicago for the President's Trophy, trailing by four points before the Blackhawks played on Saturday night.
The Bruins, beginning a stretch of six games in nine days because of two bombing postponements, lost their fourth straight (0-3-1) and were trailing Montreal, also playing Saturday night, for the Northeast Division lead and No. 2 playoff seed.
Tomas Vokoun stopped 38 shots in improving to 12-4 on the season, Brad Marchand beating him with his 17th goal of the year in the first period. Tyler Seguin scored his 16th goal with 12.6 seconds left.
Marchand took a roughing penalty, leading to Iginla's goal.
Jussi Jokinen, also picked up by the Penguins at the trade deadline, had a goal and two assists, giving him four goals and seven points in six games with the Penguins, who have 34 victories this season.
Jokinen assisted on both power play goals, Iginla scoring the 528th goal of his Hall of Fame career and 12th this season, three with Pittsburgh.
Letang scored his fifth goal scored 3:46 later.
Jokinen beat Tuukka Rask to tie the game 5:10 into the second period.
Iginla was booed every time he touched the puck and was involved in a fight while playing his usual efficient game.
The Bruins might have suffered damage to their playoff chances, as they lost Nathan Horton and Adam McQuaid to injuries.
Horton appeared to injure his right hand in a first period fight with Jarome Iginla, landing on the hand when the players hit the ice.
Then, in the second period, Matt Cooke's hip check left defenseman McQuiad crawling to the bench and he had to be helped down the runway to the locker room.
However, McQuaid returned to the bench late in the second period and played in the third.
Asked before the game to describe his emotions on a most-unusual Friday, Bruins coach Claude Julien said: "The same as everybody else. When those things happen in your city it's a normal thing to be a little bit, obviously, concerned, and like everybody else, extremely happy when they finally got the second suspect.
"At least we could all breathe a little easier and sleep a little easier. And now it's, hopefully, time to work ourselves into trying to get things back to normal again, but it will always leave a scar somewhere. There's some damage done, but now we have a job today, and that unfortunately is what our responsibility is."
The Penguins were hunkered down in their hotel Friday.
"Clearly, we're all watching for days now and being here and being in the hotel being inside kind of certainly became a part of the situation and a part of what the city of Boston was going through," coach Dan Bylsma said.
"And I think although we weren't a part of it, the celebration outside as a city and as a people last night, and just feel like it's a great opportunity to play a game with the city of Boston, not just against the Bruins but with the city and with the Bruins."
NOTES: Boston scratched a healthy but struggling Milan Lucic, while Carl Soderberg, who just came over from Sweden with a three-year contract, debuted. ... The Bruins wore baseball caps saluting Boston, Watertown and State police forces in pre-game warm-ups, many of the players tossing the caps into the stands after the skate. At the other end, the Penguins had "Boston Strong" T-shirts under their jerseys, complete with the Bruins' logo, and "Boston 617" decals on their game shirts (and helmets), along "Boston Strong" ribbon decals. The jerseys are to be auctioned off for "The One Fund," aiding victims of the bombings and their families. Pittsburgh coach Dan Bylsma also sported a T-shirt before the game. ... National Anthem singer Rene Rancourt again led the crowd in a loud rendition of the anthem, with a "U-S-A" chant going up when the song ended. This all followed a video tribute to Friday's local heroes and the four people murdered by the alleged bombers. ... There was a police and military presence outside TD Garden before the game. The Penguins visit Ottawa on Monday and then host Buffalo on Tuesday, that game re-scheduled from Saturday night to accommodate the Bruins. Boston hosts the Florida Panthers Sunday. ... A SWAT vehicle with a Bruins' logo on it was visible at the scene Friday. "It was the battering ram, right? That's that the first thing somebody sees coming through; that's pretty cool. I saw that and I hope I never have to see that up close," Boston's Andrew Ference said with a laugh. "That was pretty awesome to see those guys do that, and I'm not surprised because those guys, they've always been big Bruins' guys. They're always pretty eager to share how passionate they are about hockey." ... Bruins TV announcer Jack Edwards apologized on Twitter for comparing Pittsburgh's Matt Cooke, an old Bruins enemy, to Robert Kennedy assassin Sirhan Sirhan.