Kilgour's second three-pointer gave the Falcons, who will host a quarterfinal contest Friday against fifth-seeded El Toro or 12th-seeded Huntington Beach, a 37-30 lead with 6:11 left in the third quarter.
"After halftime, we started running our plays and we got some momentum," said Kilgour, who finished with a game-high five three-pointers and 19 points. "We had to contain their guards because they were beating us on the pick-and-rolls in the first half."
Crescenta Valley, which finished second in the Pacific League before posting a 74-56 opening-round home win against Colton on Friday, also got 17 points and four assists from forward Davis Dragovich to eliminate Warren (19-10).
Dragovich had three offensive rebounds and nine points in the second half.
"We knew we had a size advantage and we came out sluggish in the first half," Dragovich said. "In the second half, we took advantage of our size.
"We had to be more active and our guards were hitting their shots and we were hitting the boards."
Crescenta Valley closed out the third quarter on a 7-0 run to take a 46-37 lead. It then took a 51-37 lead on a basket by Tade Keshishyan to make it 51-37 with 6:44 remaining in the fourth quarter to complete a 12-0 run.
The Falcons got 15 points and a game-high six assists from guard Cole Currie. Currie made all nine of his free-throw attempts, including a pair when he was fouled just before time expired in the half to make it 29-28.
Junior forward Elliot Wilson registered seven rebounds for the Falcons.
Warren, which received an at-large berth from the San Gabriel Valley League before recording a first-round road victory against La Quinta La Quinta, got a team-high 13 points from Ife Kalejaiye and 12 apiece from Lorel Johnson and Joseph Campos.
