LAS VEGAS >> BYU kept turning the ball over, and Utah kept scoring.

About the only question left after five first quarter touchdowns by the Utes was how big their Las Vegas Bowl rout would be. Until BYU regained its composure, that is, and made it a game for both teams to remember.

Utah took advantage of a disastrous start by BYU, scoring five first-quarter touchdowns on turnovers — including two interceptions by Tevin Carter — before holding on Saturday to beat the Cougars 35-28.

“We ended up with the win, which is all that matters,” Utah coach Kyle Whittingham said. “It’s the only thing that matters.”

Utah used its string of first quarter turnovers to build a 35-0 lead, then managed to hold on as BYU mounted a comeback that brought the Cougars to within one score with 3:23 left in the game. BYU couldn’t get the ball back, though, losing in Bronco Mendenhall’s last game after 11 years as head coach.

“We did lose the game,” Mendenhall said. “But I’m taking with me a pretty good going away present.”

After the game, BYU said it hired former Cougars running back Kalani Sitake as head coach. Sitake was Oregon State’s assistant head coach and defensive coordinator.

Carter returned one of his picks for a touchdown and another to the 1 as No. 20 Utah romped to a 35-0 first- quarter lead in the first meeting of the two heated rivals outside of the state of Utah. BYU turned the ball over the first five times it had the ball, with freshman quarterback Tanner Mangum throwing three interceptions and fumbling once.

That was all the scoring Utah did, and it nearly cost the Utes the game. Mangum would bring BYU back, throwing two touchdown passes and rushing for another to get the Cougars close.

“Giving up was never an option tight end Remington Peck said. “Everybody had the mentality that we would somehow find a way to get back in it.”

Mendenhall’s last game as BYU coach was almost over even before some of the fans settled into their seats, thanks to an opportunistic Utah defense that forced Mangum to fumble on the third play of the game. Midway through the first quarter, the Utes were already up 28-0.

In a statistical quirk, BYU actually outgained Utah offensively (89-69) in the first quarter. But Carter and Dominique Hatfield both scored on interceptions, Joe Williams had two 1-yard touchdown runs, and quarterback Travis Wilson added another TD on a 20-yard run.

“You’re not going to lose a lot of games when you’re plus-5 in the turnover department” Whittingham said. “We got complacent and that’s on me. Next time we’re up 35-0 hopefully we won’t have the same results.”

Mangum’s shaky start didn’t stop him from throwing for 315 yards in rallying his team. BYU dominated much of the game, but couldn’t quite dig itself out of the big hole.

“I think the game was a little big for him at the beginning, but man he turned around and played a great game,” said end Bronson Kaufusi, who played his last game. “Ultimately he gave us a chance to have the ball at the end.”

Utah (10-3) came in as a 2-point favorite in the first meeting since 2013 of schools that have campuses just 46 miles from each other. But the quick succession of turnovers — Utah scored its first four touchdowns in a span of 3:30 — threatened to turn the game into a rout before BYU settled down.

BYU ended up with 386 yards to 197 for Utah, but the five early turnovers were the key in a game where the Utes didn’t turn the ball over at all.

Mendenhall, who is leaving BYU (9-4) after 11 seasons to coach at Virginia, failed in his try at win No. 100 at the school. Mendenhall, who wanted to coach the bowl game before leaving, finished his BYU career with a 99-43 record.

I’m not sure I’ve ever been more proud of my team,” Mendenhall said. “They stayed together and unified and battled back and made it a great football game. Our team tried really, really hard all the way to the very end, maybe if we make one more stop it gets interesting.”

Mangum, who earlier this season led the Cougars to last-minute comebacks against Nebraska and Boise State, never had a chance to do the same against the Utes. After bringing them within a touchdown with 3:23 left, he could only watch on the sideline as the Utes picked up two first downs and ran out the clock.

BYU was down largely because of the early mistakes by the freshman, who lost a ball while scrambling on the third play of the game, then threw interceptions on the next three drives. Coming into the game, Mangum had thrown just seven picks all year.

Mangum ended up completing 25 of 56 passes for 315 yards. Wilson was 9 for 16 for 71 yards.

Utah, which at one point in the season was 6-0 and ranked No. 3, had 19 interceptions in the regular season, seventh best in the country. The Utes wasted no time adding to that number with two picks on tipped passes by Carter followed by a 46-yard interception return by Hatfield for a touchdown.

The win before a sellout crowd of 42,213 was the ninth in 10 bowl games for Whittingham as head coach of Utah. The Utes have won 12 of their last 13 bowl games.