DETROIT — Only two people in a stadium full of 30,000-plus people were unaware of the impending disaster.

The rest were staring, transfixed, as the two outfielders raced headlong toward each other — and a collision — with the inevitability of two demolition derby cars.

“It looked like it could be a problem,” said Detroit Tigers manager Brad Ausmus, as he watched his center fielder, Don Kelly, on a collision course with right fielder Torii Hunter, both chasing after a long fly ball off the bat of Lorenzo Cain in the seventh inning of Monday’s game.

“And that happens sometimes in the outfield. Guys are running full speed, trying to make catches, the noise in the stands rises, and they don’t hear each other, and they do collide.”

Kelly appeared to call for the ball. But he didn’t see Hunter, not even out of his peripheral vision.

“At the last second (I saw him). It’s one of those balls that is right in between. I didn’t hear him call it, and I called it late, because I didn’t know if I was — I didn’t want to call it and not be able to get there,” Kelly admitted after the game.

“I called it late, and he was already committed. It was just one of those freak plays that was right down the middle.”

The ball settled into the pocket of Hunter’s glove, for a split second, at least, before it was jarred loose by the collision with Kelly. Hunter fell hard, and hit his head on the ground. [WATCH THE VIDEO HERE]

Kelly, who’d hit the ground too, just not as hard, didn’t know where the ball went.

“Yeah, but I didn’t know where the ball was. I heard it hit his glove, and then I saw the glove laying there. But I didn’t see it,” said Kelly who, thinking the ball might still be in Hunter’s glove, went back to check, before the right fielder pointed to where the ball was lying, 15 feet away, against the wall. “I did. Because I heard it go in his glove. That’s why I checked his glove, because I thought maybe his glove came off with the ball still in it. But I must’ve knocked the ball out when I ran into him.”

Meanwhile, Cain zoomed around the bases for the 95th inside-the-park home run in Royals history, and the first allowed by the Tigers in more than a calendar year. More concerning to the Tigers was the health of Hunter, who stayed down, even after the conclusion of the play.

“I was fine. I didn’t hit my head off the ground. I hit the ground, but not like he did,” Kelly said. “Unfortunately, I hope he’s OK.”

That was why Ausmus and head trainer Kevin Rand went running out to check.

“Well, the first concern is concussion. Looked like he had hit his head. But Kevin Rand ran some questions by him. He was much more responsive than Alex (Avila, who missed three days with concussion symptoms) was the other day in Cleveland. He seemed OK out there. He answered all the questions correctly,” Ausmus said.

“We did end up taking him out after he scored in the bottom of the eighth. He said he had a little bit of a headache. So we took him out for that reason — just precautionary. They tested him again underneath the dugout when he came out of the game, and Kevin Rand said he tested just fine. We don’t expect it to be an issue, but we just wanted to get him out of there with an overabundance of caution.”