LOWELL — Junior defenseman Dylan Zink scored a hat trick before the game was half over and Adam Chapie added a pair of goals nine seconds apart in the second period as the University of Massachusetts Lowell unleashed a torrid offense to defeat Boston University, 6-3, on Saturday night before 6,013 at Tsongas Arena.

“It seemed like every mistake we made ended up in the back of our net,’’ said BU coach David Quinn.

No. 11 Lowell (18-7-5, 11-5-4) remains in fourth place in Hockey East, holding off fifth-place BU (17-9-4, 10-5-3) in the standings by 3 points after winning the back end of the teams’ home-and-home series.

The top four teams in the conference earn home ice and a first-round bye in the Hockey East tournament. Lowell has three conference games remaining, while No. 7 BU has four.

“It’s obviously a very good win,’’ said Lowell coach Norm Bazin, whose team dropped a heartbreaker on a power-play goal in OT Friday. “I thought there were a lot of guys contributing . . . with shot blocks, with taking away time and space, so we were better tonight.’’

The Terriers outshot the River Hawks, 38-29, and there were 30 shots blocked by Lowell’s defense. “Today I thought the guys responded [after Friday’s loss],’’ said Bazin, “and that’s a category where they showed some urgency.’’

Lowell’s defense ranks second in the nation, allowing 1.77 goals per game.

Zink, who couldn’t remember the last time he got a hat trick — “not since Squirts or something,’’ he said — got the first hat trick for a Lowell defenseman since Dave Barozzino on March 16, 1996, against Michigan State.

“I give a lot of credit on the first two goals to net-front presence,’’ Zink said. “The goalie couldn’t even see it.’’

Zink opened the scoring at 11:26 of the first with a shot off a faceoff at the left dot, lifting a shot from the edge of the circle into the top right corner.

BU’s Bobo Carpenter evened the score at 13:02, collecting the rebound of his own backhand shot and skating behind the net, coming out on the right side to tuck in a wraparound.

Zink restored the River Hawks’ lead at 17:46, off another faceoff at the left dot. This time Michael Kapla got the puck to Zink at the center point and he scorched his slap shot through a screen.

Zink completed his natural hat trick at 3:13 of the second with another shot from the left circle on a feed from Nick Master. It was Zink’s ninth goal of the season. Not long after, at 5:40, Connor LaCouvee replaced Sean Maguire in the BU net.

The River Hawks’ offense did not slow.

“We just tried to get the puck behind them and get to pucks first,’’ said Chapie. “We wanted to have a good puck-possession game and it starts with getting the puck deep and getting first touches so we can start the offense.’’

Soon enough it was Chapie’s turn. The senior winger took Joe Gambardella’s pass at the left side of the net and slipped in his first at 10:14, then came right back to finish off a give-and-go with Jake Kamrass at 10:23 that made it 5-1. It was the fastest two goals in Lowell history since the program moved to Division 1 in 1984.

“They scored to tie but we scored the next four,’’ Bazin said. “That certainly loosened things up. From that standpoint, hey, it’s OK to feel good about yourself and sometimes you need a game like this to get going.’’

Oskar Andren closed BU within three at 14:52 but in a relatively quiet third period, A.J. White batted in the rebound of a Ryan Dmowski shot at 15:13 for the four-goal lead. Brandon Fortunato got one back for BU at 17:45.

“I actually thought we were ready from the get-go,’’ said Quinn. “Then first goal, loose coverage in the D-zone and obviously Zink had his way. Disappointed in the outcome, disappointed in why we lost the way we did.’’