SEATTLE — Lexi Petersen’s three pointer banked in, but it was too late.

Oregon had the ball with 5.6 seconds left and the opportunity to drill a game-winner, but the buzzer sounded just before Petersen’s shot, ending the Ducks’ season in heartbreak fashion. Washington State walked away with a 66-64 win at Seattle’s KeyArena on Thursday afternoon.

The Ducks’ three games this season with Washington State have been decided by six total points.

Jillian Alleyne tallied her NCAA-best 28th double-double with 18 points and 18 rebounds. Petersen had 12 points and Lexi Bando, in her first game back after missing two games, had 11 points.

“I thought down the stretch (WSU) appeared to maybe want it a little more,” head coach Kelly Graves said. “I thought we fought hard today and fought hard all season. We never gave up.”

Washington State’s Lia Galderia had a career-high 34 points on 14-of-24 shooting, while grabbing a team-high six rebounds.

“When Lia Galdeira does that, there’s not a whole lot you can do,” Graves said.

The Ducks took an early 6-2 lead, but WSU quickly tied it up at 9-9 with 16:14 before halftime.

Oregon went on a 12-2 run to take a 26-17 lead following a Katelyn Loper three-pointer with 7:29 left before the half. Alleyne scored her first career three-pointer during that stretch.

Seven Oregon turnovers led to 11 of WSU’s first 13 points to open the game.

“I saw an opportunity and I took it,” Alleyne said of her three-pointer.

After WSU roared back to take the lead, 30-29, the Ducks put together a 9-0 run to retake the lead 38-30 with 21 seconds before half. WSU’s Louise Brown hit a three-pointer at the buzzer to send the Ducks to the locker room with a 38-33 lead.

WSU led by eight points, 61-53, with 6:17 to go, but another Loper three-pointer got the Ducks back in the game. Galdeira hit a three-pointer with 2:29 left, but Petersen answered with a layup to make it a four-point WSU lead with 2:00 to go.

“I thought we were ready to play,” Graves said. “It was a fun game in terms of runs. Both teams were getting leads and the other would battle back. In the late second half, it was basket-for-basket.”

Drea Toler forced a WSU turnover with 1:05 left and made the ensuing bucket to cut the WSU lead to two points. Toler missed a contested layup with nine seconds left that would have tied the game.

“It took us a little bit to get the outlet to Drea and then I think she wanted to make a pass a second earlier and couldn’t,” Graves said.

Oregon’s 54 percent shooting from the field is its best since the season opener against Utah State (54.8 percent).

The Ducks, who finish the season 13-17, 6-12 Pac-12, have shown themselves to be resilient this year.

“They left it all out on the floor, no doubt about it,” WSU coach June Daugherty said.

Oregon will lose four seniors (three on scholarship) for next season. The Ducks currently have three players signed to letters of intents to play in Eugene next season, though Graves has said he hopes to add more before the signing period ends.

“I’m proud of how we competed and played and conducted ourselves on and off the court, in the class room,” Graves said. “It’s been a really good group.”

Notes: The Ducks lost, despite outshooting Washington State 54 to 42.2 percent. … Oregon committed 17 turnovers compared to WSU’s seven. … Katelyn Loper finishes her Oregon career tied eighth all-time with Chelsea Wagner (2003-2006) with 133 made three-pointers. … The Ducks have now lost seven-straight Pac-12 Tournament games. … Lexi Bando said her injury was a sublexed left shoulder, “It partially popped out at practice.”

Follow Jonathan Hawthorne @Jon_Hawthorne