NEW YORK -- Yankees right-hander Masahiro Tanaka was treated and released from a local hospital on Saturday after being struck in the head by a line drive off the bat of Giancarlo Stanton, a frightening scene that cast a somber tone over the first formal workout of Summer Camp at Yankee Stadium.

Tanaka had faced several hitters in a simulated game when Stanton connected with an offspeed pitch, lacing a liner back toward the mound. The ball appeared to hit Tanaka on the right side of the head, and the hurler dropped to the dirt as his cap flew off. Tanaka was not utilizing a protective screen.

The Yankees said that Tanaka is alert, responsive and walking under his own power. He was sent to New York-Presbyterian Hospital for further evaluation and testing, including a CT scan, which was negative. Yankees manager Aaron Boone said Tanaka showed post-concussion symptoms and, though they subsided, he will be placed into concussion protocol.

“Anytime you see that on a baseball field -- and then add in there that it's a teammate -- that stops you in your tracks,” Boone said. “You hope for the best. When I went out to the mound, at least in the immediate I felt somewhat good about it because he was alert and very aware. There was a little relief there, but you always worry about the next minutes and hours. The fact that we're getting good news is a good thing.”

Stanton instantly crouched at the plate, then stood on the infield grass with his hands on his hips as medical staff attended to Tanaka, who showed minimal motion for several minutes before he was helped to his feet.

“Right away, I checked in on G as well; just how you doing, you OK?” Boone said. “I think [there was] a little bit of relief to see him walk off, and then we were able to let G know a little bit later that [Tanaka] was doing well. I don't necessarily want to speak for G, but he seemed to handle it as well as could have been expected.”

Tanaka returned to New York this week, having traveled back to Japan with his family shortly following the conclusion of Spring Training on March 12. He is envisioned as one of the key members of the Yankees’ rotation, along with Gerrit Cole, James Paxton, J.A. Happ and Jordan Montgomery.

“You step onto the field and anything can happen,” outfielder Aaron Hicks said. “It just kind of sucks it had to happen to him.”

When activity resumed on the field, several teammates appeared to be shaken by the injury. Montgomery took over on the mound, opting to use a protective screen for his simulated game.

“I was a little timid after seeing that, a little squirrely,” Montgomery said. “That's kind of a freak accident, a one-in-a-million chance of happening. And then it does, it's terrifying. Especially as a teammate and friend, you don't want to see anybody hurting. It's really hard to see. We're all thinking about him and hoping for the best.”

Boone said the Yankees give their pitchers the option of using a protective screen during live batting practice and simulated games.

“Masa did not want it,” Boone said. “You’ve got to get out there at some point without it. As we get into live BPs and intrasquad situations, guys will have it out there, some guys won't. Obviously it's incredibly unfortunate what happened today, and in a lot of ways we're hopeful that we avoided something really bad happening. Unfortunately, that's sometimes the risk that goes along with it.”

The 31-year-old Tanaka is beginning his seventh season with the Yankees, having compiled a career record of 75-43 with a 3.75 ERA to date. Tanaka was 11-9 with a 4.45 ERA in 32 games (31 starts) in 2019.