LOWELL, Mass. — Hilary Knight scored her first career hat trick, Aerin Frankel made 38 saves and the Boston Fleet completed a season sweep of the New York Sirens with a 5-2 win on Wednesday night.

Knight, who scored her third goal into an empty net with less than 10 seconds to play, also had an assist for Boston (7-5-3-6, 34 points), which moved into second place ahead of Toronto.

Six of the Fleet wins have come against New York, including two in shootouts with Knight scoring five goals and adding seven assists. Alina Muller had a goal and two assists, Susanna Tapani had an assist plus her ninth goal in the third period and Shay Maloney had two assists.

Frankel, who matched her season high for saves, has been in net for all six wins over New York, which outshot the Fleet 32-11 through two periods before being outshot 9-8 in the third.

The last-place Sirens (4-3-4-10, 22 points) are winless in nine games and Elizabeth Giguere’s game-opening goal was just the second time they scored first in the skid.

Muller tied the game with her sixth goal in the first period.

Knight scored on a power play and a breakaway for a 3-1 Boston lead. New York rookie Sarah Fillier got her eighth goal on a power play and moved into a tie for the league lead with 22 points to cut the deficit to 3-2 entering the third period. Knight has 21 points, including 11 goals.