BOSTON — Simon Gagne and the Philadelphia Flyers put together one more comeback to finish off the Boston Bruins' collapse.

Taking advantage of a too-many-men-on-the-ice call, Gagne scored on a power play with 7:08 left to give Philadelphia a 4-3 victory last night in Game 7 of the Eastern Conference semifinals.

The Flyers overcame a 3-0 series deficit and a 3-0 hole in the first period, rallying to advance to the conference finals against Montreal.

"It's just a great feeling," Scott Hartnell said. "All the adversity we had fought through, being down, 3-0, in the series, 3-0 in the game, to come back and win, it's absolutely incredible."

It was humiliating for the Bruins, who became the third team in NHL history to lose a series after winning the first three games.

"We got a little carried away from our game plan and lost our composure" in Game 7, Bruins captain Zdeno Chara said.

When the final buzzer sounded, the Flyers poured off their bench and surrounded Michael Leighton, who held the Bruins scoreless in the last two periods after starting just his second playoff game for injured Brian Boucher.

The decisive penalty occurred with 8:50 left and Gagne, a force since returning from a toe injury for Game 4, scored with 18 seconds left in the power play.

"I saw two centermen out there and I said, 'What's going on,' "said Milan Lucic, who had two goals for Boston. "I knew there was a miscommunication out there and we got caught."