As hundreds strolled into McNeice Pavilion on Tuesday evening, administrators found themselves scrambling to find extra folding chairs for the stragglers.

For BC High basketball fans, the playoff game that followed was worth the price of admission. Sophomores Owen Adams (18 points) and Charlie Anzenberger (13 points) got their team off to a flying start. Meanwhile, senior Jacob Seyfried (15 points) sealed the deal in the second half as the fourth-seeded Eagles dispatched No. 13 Brockton in the Div. 1 Round of 16 with a commanding 64-45 victory.

“It was huge,” Seyfried said. “I mean, that was the biggest crowd that we’ve had in a long time. Just the fact we were able to keep our composure, and stay with the high energy the whole game is really impressive. It was a team effort tonight.”

You could hear the roar of the fans from nearby Castle Island, as the two schools exchanged punches in the game’s opening minutes. Brockton (14-8) came ready, as Nyisah Miranda sank a pair of three-pointers right out of the gate to give the Boxers an early 8-5 advantage.

As they have done so often this winter, the Eagles (16-6) answered with authority. Adams knocked down a triple himself, sending the school’s student section into pandemonium as BC High jumped in front, 10-8, with 4:15 to go in the opening frame.

BC High’s George Bracher makes Brockton’s Marcus Fortes lose the ball during the first half of a boys basketball game. (Photo By Matt Stone/Boston Herald)

The Eagles never trailed again. Adams sank a layup moments later as part of a 10-0 run, helping BC High push its lead to 19-13 at the end of the first.

After the Boxers cut it to a 21-18 contest at the start of the second quarter, Anzenberger caught fire. The sophomore guard drilled a pair of three-pointers as part of a 12-3 run, and the Eagles had suddenly seized control, leading 33-21 with just under two minutes remaining in the half. They would take a 33-24 advantage into intermission.

“With the flow of the game, I was just finding my spot,” Anzenberger said. “Just a good flow of the game, and I hit my shots.”

Brockton tried to stage one more rally to open the second half, cutting it back to a six-point contest at 38-32. Then, BC High delivered the finishing blow with Seyfried leading the charge.

The senior guard registered nine of his points in the third quarter alone, fueling a 13-0 run to make it a 51-32 game. The Eagles cruised to an appearance in the state quarterfinals from there.

“I think the kids responded, did a great job,” Eagles coach Bill Loughnane said. “The student body came out, and were supportive for their classmates. This time of year, it should be a great environment. They practice for this, they’re lucky enough to get a chance to play in it, and it was really nice the way that they responded. So, I’m happy for them.”

Brockton’s Jayden Holes Fox swats the ball from BC High’s George Bracher during the second half of a boys basketball game. (Photo By Matt Stone/Boston Herald)

Miranda finished with 13 points to lead Brockton, while Marcus Fortes added 12 points for the Boxers.

Since taking over at BC High in 2005, Loughnane has coached many great teams. This year will mark his latest trip to the state’s quarterfinals with the Eagles.

“It never gets old,” Loughnane said. “Like I always say, if you can win one in the tournament, you’ve had a good year. If you win two, it’s a very good year. Then, after that, you might as well go for everything. I think these kids are really excited about going on.”