SAN DIEGO -- Philadelphia Phillies outfielder Bryce Harper has a broken left thumb after being hit by a 97 mph fastball from Blake Snell in the fourth inning Saturday night against the San Diego Padres.

The Phillies announced that the reigning NL MVP will be out indefinitely. He will undergo further evaluation in the next few days.

Harper checked his swing as the pitch from Snell rode inside and high before hitting him on the outside of the left hand. Harper immediately fell to the ground and was in visible pain as he held the hand while on his knees for several minutes with Phillies head trainer Paul Buchheit attending to him.

Phillies general manager Dave Dombrowski, who traveled with the team on the road trip, said it was too early to determine if surgery will be needed. He added that he wasn't sure what type of fracture Harper had or where on his left thumb the injury occurred.

"We will put him on the injured list [Sunday]," Dombrowski said. "I was concerned at first he got hit in the face. I was concerned right off the bat because he is a tough guy and he walked off the field immediately."

As Harper was halfway to Philadelphia's dugout, he angrily yelled at Snell and motioned with a hand at the Padres' starting pitcher. Snell eventually shouted back at Harper. Many of the fans at Petco Park fans started to boo Harper after several seconds with Harper shouting at Snell.

Harper then appeared to cool down and say, "I know, I know," to Snell, acknowledging that the pitcher didn't mean to hit him with the pitch.

"He knows [Snell] wasn't trying to throw at him," Dombrowski said. "It was just an emotional time. He has had bad luck -- last year he was hit in the face and this year he has had a couple of injuries."

Harper, serving as the Phillies' designated hitter, was replaced by Johan Camargo in Philadelphia's 4-2 win.

"He is a guy who really isn't replaceable on an individual basis, but we are going to have to be in a position that other people are going to have to step up," Dombrowski said. "We will make a move to try and get someone here [Sunday]."

Harper is hitting .318 with 15 home runs, 48 RBIs and a .984 OPS this season in 64 games despite a small tear in the UCL of his right elbow that has prevented him from playing the outfield since April 16. He has tried to avoid season-ending Tommy John surgery with a platelet-rich plasma injection and rest.

"I don't know how long he is going to be out at this point," Dombrowski said. "I am hopeful he will be back at some point. We still have a lot of good hitters in the lineup. ... The Braves won the World Series last year without [Ronald] Acuna."