Some teammates raced toward the mound, others broke obligatorily to play the ball, still others stood paralyzed in the field.

Blue Jays left-hander J.A. Happ had delivered a fastball to Desmond Jennings with the count at three balls and one strike in the second inning. Jennings’s line drive back to the mound struck him directly in the left side of the head, likely at a speed of about 100 mph. The ball ricocheted past first base and into the Rays bullpen in foul ground.

When the play ended, Jennings standing on third base with a two-run triple, medical personnel rushed to Happ as he lay prone on the front of the mound, the Tropicana Field crowd of 10,723 standing in stunned silence.

“You don’t know what to think,” said fellow starter R.A. Dickey, after the Jays defeated Tampa, 6-4, with two runs in the ninth inning on a Maicer Izturis solo homer and an RBI double by Melky Cabrera. “When you hear the sound off the bat and it sounds like it hits another bat, it’s scary. It’s really scary, and you just start praying.”

Happ was transported to hospital. Manager John Gibbons said he was undergoing tests, and the club could not update his condition.

The first optimistic sign occurred as Happ raised his hand to the side of his head on the mound, and his legs moved. Following an 11-minute delay, medics wheeled him off on a stretcher to be transported to the hospital. He waved weakly as the stretcher exited the field.

“His knee was kind of bugging him and he wanted to turn his knee over and we told him to stay put,” third baseman Brett Lawrie said. “It’s tough to see a guy like that go down. It’s scary. Play continues, and you don’t know he’s doing, or what’s happening. It’s just a bad situation, bad, bad. But he was conversing and I hope he’s going to be alright.”

Brad Lincoln replaced Happ on the mound, the first of four relievers to shut down the Rays the rest of the way, as the offence recovered from a 4-1 deficit.

“It’s on your mind, definitely, but you’ve just got to go out there and bear down,” said Lincoln. “You don’t really think about it when you’re out there on the mound. Then when you see it happen it makes you step back and think, there’s always that possibility. When it happened, I kind of had an idea it would be me, and it’s on the back of your mind but you just try to move on and get past it.”

Happ was injured exactly 56 years after one of the most frightening incidents in baseball history. Herb Score of the Cleveland Indians suffered broken facial bones and an injured eye from a line drive hit by Gil McDougald of the New York Yankees. Score was never again as effective, though historians have written that he refused to cite that incident as the reason.

Much more commonly, pitchers withstand the injury. In the last two months of the 2012 season alone, Doug Fister of the Tigers was hit on the side of the head during Game 2 of the World Series in the same manner as Happ, at the end of his delivery with his weight on the plant foot. Fister remained in the game after being struck by Gregor Blanco’s line drive. On Sept. 5, 2012, a line drive off the bat of the Angels’ Erick Aybar struck Oakland pitcher Brandon McCarthy on the right side of the head, fracturing his skull and causing an epidural hemorrhage. He needed two hours of brain surgery. A week later, on Sept. 12, Dave Sappelt’s liner deflected off Mickey Storey’s pitching hand before hitting him in the jaw. He walked off with the help of trainers.