BOSTON — Bobby Ryan tipped home a pass from Kyle Turris for a power-play goal 5:43 into overtime, giving the Ottawa Senators a 4-3 victory over the Boston Bruins on Monday night and a 2-1 lead in the first-round Eastern Conference playoff series.

Riley Nash was in the penalty box for taking a swing at Ryan when Erik Karlsson hit a flying Turris with a pass into the zone that was close to being offside.

Turris then got the puck to Ryan, who tipped it past Tuukka Rask as the Senators overcame blowing a 3-0 lead to recapture home-ice advantage in the best-of-seven series.

When the game ended, Bruins fans, irate over the penalty call, littered the ice with debris.

The assist was the second of the game for Karlsson. Ryan scored his second goal of the series as the Senators captured their second straight OT victory.

Craig Anderson made 17 saves in the Ottawa goal, and Rask had 28 saves for Boston.

Game 4 is Wednesday night at TD Garden.

Mike Hoffman scored twice and Derick Brassard had a goal in regulation for the Senators.

Noel Acciari, David Backes and David Pastrnak answered for the Bruins in their second straight three-goal second period. The three goals were scored on just seven shots in the period. The Bruins had just 10 shots through two periods.

Defenseman John-Michael Liles had two assists for Boston.

The Senators struck for two goals in 25 seconds in the first period, with Karlsson setting up both.

Karlsson’s long pass was right to a breaking Hoffman, who deked and scored with one hand on his stick, slipping the puck just by Rask. Karlsson then made a nifty play at the blue line to keep the puck in but didn’t get an assist as Brassard took a pass from Ryan and made it 2-0 with his 20th career playoff goal.

The Bruins went the final 9:47 of the first period without a shot and had one in the final 16:18.

The home crowd, already uneasy, saw the Bruins give up another one when Hoffman scored again on the power play at 3:42.

Things then changed quickly, with Liles’ flip from the left point deflecting in off Acciari, who was returning from injury for his playoff debut.

Then, 42 seconds later, Ryan couldn’t handle the puck in the own zone. Backes picked it up and went in alone to beat Anderson.

Pastrnak tied it 5:01 later with a power play blast off a pass from McAvoy.

NOTES: C David Krejci, who missed the first two games of the series with an upper-body injury, returned for Boston. … Ottawa D Mark Borowiecki, who sustained a lower-body injury in Game 2, was replaced by Ben Harpur, making his playoff debut. … D Tommy Cross, a Boston College product, made his playoff (and also his 2016-17) debut with the Bruins, who were missing four defensemen because of injury. Colin Miller skated in warmups but did not play. … Senators D Erik Karlsson skipped the morning skate. Coach Guy Boucher said, “He never needs to practice.” … The original Ottawa Senators defeated the Bruins for the 1927 Stanley Cup in a four-game sweep. … Boston Marathon finishers were asked to rise for the cameras during a first-period timeout. … The Bruins sent D Matt Grzelcyk back to AHL Providence during the game.