Dean Mazlish leaped three times as if there were a trampoline underneath him, using the seconds before his teammates mobbed him to process the reality that his Sidwell Friends boys’ basketball team was the D.C. State Athletic Association Class AA champion.

Seven seconds earlier, with No. 19 Sidwell Friends trailing by two, Mazlish dribbled past Wilson’s full-court press and ignored Coach Eric Singletary’s play call, thinking there was too little time.

Then the senior guard crossed over his defender with a behind-the-back dribble and sank a three-pointer just before the buzzer, delivering the Quakers their first DCSAA title with a 63-62 overtime win over No. 1 Wilson at Entertainment and Sports Arena in Southeast Washington.

“This is the best feeling,” said guard Jason Gibson, who scored a game-high 24 points. “To win it means everything.”

Sidwell Friends (25-7) became accustomed to the dramatic this tournament to reach its first title game. The Quakers beat McKinley Tech in the quarterfinals with an overtime buzzer-beater and upset No. 3 St. John’s in Friday’s semifinals.

Wilson guard Dimingus Stevens finished a breakaway layup to give his team a two-point edge with about seven seconds remaining. The Tigers (31-9), who added Maryland signees Makhi and Makhel Mitchell in the offseason, were close to repeating as DCSAA champions.

Gibson, who had been the Quakers’ hero all season, fouled out in overtime. So Sunday became Mazlish’s moment.

“I didn’t have any time to contemplate what happened,” Mazlish said. “I’ll check Twitter and be like, ‘Oh, my god.’ It’s going to be crazy.”

Sidwell Friends is known as an academic school and as the home for politicians’ children, such as Chelsea Clinton and Sasha and Malia Obama.

Singletary, who played at Sidwell Friends in the early 1990s, has heard the stereotypes about the Quakers over his 11 years coaching the Northwest Washington private school. He only recruited players who could thrive in academics at Sidwell Friends and pitted his teams against the area’s top private schools in summer leagues.

Josh Hart of the Los Angeles Lakers played at Sidwell Friends in the mid-2010s, and the program has only grown since.

As Sidwell Friends posed for photos with the championship banner, Singletary couldn’t stop repeating to himself: “Are you kidding me?” Then he grabbed the plaque and ran into the crowd to celebrate with the Quakers’ fans.

“This one,” Singletary said, “lets people know we’re really here.”

KIPP wins Class A

In the earlier game, KIPP won the inaugural DCSAA Class A boys’ championship with a 55-47 win over SEED.

Guard Saveon Jackson led KIPP (22-5) with 21 points, eight rebounds and seven steals. The Panthers expect to return their five leading scorers next season, including Jackson.