The breeze you may have felt around 9:45 p.m. might have been from some 18,000 people collectively exhaling on Causeway Street on Thursday night.

After racing out to a 4-0 lead in the first two periods, off the strength of three goals in 54 seconds in the first period, the Bruins survived by their fingernails a third-period push from the Vegas Golden Knights and escaped TD Garden with a 4-3 victory.

The Knights, thoroughly outplayed in the the opening 40 minutes, outshot the B’s 20-5 in the third period and scored three unanswered goals. But they needed to get four, and the B’s squeaked out the two points.

Afterward, coach Marco Sturm wasn’t ready to apologize for the victory.

“I still see it as a positive,” said Sturm. “Yeah, the way we started the third, just two mistakes that shouldn’t happen from the guys who’ve been around. But we knew when they scored early, we just had to be careful. They are a good team but overall, I liked our response today (from Tuesday’s blowout loss in Dallas). It was probably one of better 40 minutes of hockey, so that’s why I see it as more of a positive.”

Joonas Korpisalo turned away 29 shots — over half of which came in the third — to nail down the victory. He has now won four straight. Though he only saw 12 shots in the first two periods, Korpisalo did have to make several high danger chances, especially in the first period when the game was scoreless. There were points in the third period when Sturm could have called his timeout to stop the bleeding, but he said Korpisalo’s play gave him reason to believe that his players were going to hold on.

“For some reason, I was very calm. I trusted my guys. I thought about it but, again, I was pretty calm,” Sturm said.

Sturm might have been the only one in the building who was, but they did hang on.

This one looked like a Bruins romp at first.

When Tomas Hertl was called for a double minor for high-sticking at 9:01 of the first period, the B’s took full advantage of it. Eleven seconds after Hertl took a seat in the box, Charlie McAvoy’s one-timer from out high beat netminder Akira Schmid for his fourth of the year.

With the B’s still on the power play, they doubled the lead just 30 seconds later. David Pastrnak (1-2-3 totals) found Elias Lindholm in the slot and the centerman scored his ninth of the year over Schmid’s blocker.

The team’s went back to even strength, but the B’s were not done.

Tanner Jeannot created a turnover in the Vegas zone, poking it free from defenseman Ben Hutton, and Sean Kuraly pounced on the loose puck. Kuraly fed it back down to Jeannot and, from the left wing, Jeannot beat Schmid to the short side with a snipe at 10:06 for Jeannot’s fifth.

The B’s were skating downhill at this point and Mark Kastelic absolutely laid out Shea Theodore along the end boards. At that juncture, the Knights had to respond and old friend Jeremy Lauzon dropped the gloves with Kastelic. To the crowd’s disappointment, Kastelic lost his balance before any real shots were thrown and the linesmen stepped in to end it.

The B’s, who held a 15-4 shot advantage, nearly took a 4-0 lead but Schmid made a great blocker save on Pavel Zacha in the waning moments of the first.

Though the Knights came out with a little more purpose in the second, Pastrnak (21) did get that fourth goal at 7:25 of the second when Nikita Zadorov showed off both his brawn and skill.

From the left side of the neutral zone, Pastrnak tossed an area pass down the right wing that Zadorov chased down. With the 6-foot-3, 220-pound Hertl bearing down on him, Zadorov dropped him with a wave of his arm as he protected the puck and backhanded a pass back to Pastrnak, who ripped it past a helpless Schmid.

It was a great two periods.

“We didn’t want to waste any time,” said Pastrnak. “Before Dallas, we were playing some good hockey for a couple of weeks. It was good refreshment going back home. That’s where we’ve been playing good. We were just trying to bounce back and remember what would make us successful in the previous games. We had a great start. The first 40 minutes we were fun to watch. Special teams were there and Korpi was amazing.”

But Vegas was not going to roll over like the Rangers did here in the B’s most recent homestand.

The explosive Knights made things a little uneasy when they were able to get on the board just 31 seconds into the third, when one Boston area homeboy, Noah Hanifin (Norwood) beat Viktor Arvidsson out high and passed it to another, Jack Eichel (North Chelmsford), to make it 4-1.

Then they cut it to a two-goal deficit at 3:01 on a power play with Marat Khusnutdinov in the box for roughing, with Hertl scoring from the slot.

Things got really tight when, 45 seconds later, Jonathan Aspirot took an interference penalty. But the B’s were able to survive that one.

The Knights kept pushing though, dominating, and got to within one with 2:35 left after Schmid was pulled with 3:14 left in the third when Pavel Dorofeyev scored from the doorstep.

White knuckle time had officially arrived. With the Schmid on the bench for the extra attacker, the B’s iced the puck several times, including when Arvidsson failed to gain the red line with 53 seconds left. But McAvoy came up with a big block of an Eichel — it stung him but he was fine after the game — and Lindholm won a defensive zone draw with 1.2 seconds remaining to finally put the game to bed.