PRO FOOTBALL : Broncos, Elway Drop the Ball : AFC: Denver blows a 24-6 lead against San Diego, then loses when quarterback fumbles in the final minute.

The San Diego Chargers and Denver Broncos staged a shootout Sunday that had just about everything. San Diego won, 37-34, as Stan Humphries threw three touchdown passes and linebacker Junior Seau recovered a bizarre fumble by John Elway in the waning seconds.

San Diego turned two interceptions into touchdowns, including safety Stanley Richard’s 99-yard return for a score on the final play of the first half.

Finally, with Denver threatening at the Charger 3-yard line late in the game, Elway rolled to his right and attempted to pass. But the ball slipped out of his hand and Seau plucked the fumble out of the air at the 8 with 35 seconds left.

“I saw the ball twirling in the air,” Seau said, “and I couldn’t believe it was up there, coming from a guy who usually doesn’t make those mistakes. Elway is the best at the two-minute drill.

“We were walking the fence, but we came out a winner this time.”

A 1-yard scoring run by Natrone Means, which capped a grueling 19-play, 89-yard drive that consumed more than 10 minutes of the final period, was the clinching score.

Elway, who also had three touchdown passes, drove Denver into scoring position, helped by offside and personal-foul penalties against San Diego. But on second-and-goal, Seau iced the win.

Elway, whose 36 completions set a club record, said his critical fumble came when he had Anthony Miller “wide open in the end zone. I just lost it. It slipped out of my hand. I couldn’t believe he caught it. The interception at the end of the first half wasn’t bizarre. It was just plain stupid on my part.”

Richard’s 99-yard return capped a 21-point San Diego flurry that lifted the Chargers to a 27-24 lead at halftime.

The Broncos appeared on the verge of a rout after Elway’s second touchdown pass had given them a 24-6 lead.

Denver was driving for an apparent score in the closing seconds of the first half, reaching the Charger 5 when Elway’s pass was picked off by Richard near the goal line. Escorted by a phalanx of blockers, he scored easily as time expired in the half. Ronnie Harmon’s run on the two-point conversion made it 27-24.

Bronco Coach Wade Phillips called Richard’s interception “a 14-point swing. I’ve never seen a team get a 100-yard interception on the last play of the half. Obviously, we made too many mistakes. When you have a 100-yard interception return and you lose the ball on the 4-yard line with a fumble, you pay the price.”