The team said he was sent home to rest and his availability will be on a day-to-day basis.
The accident quickly changed the mood for the Rockies, who were regaling in the return of All-Star shortstop Troy Tulowitzki from the disabled list.
Street was taken off the field in an ambulance and transported to an emergency room for further examination.
Rockies head athletic trainer Keith Dugger said that Street passed out "two or three times" and had ringing in his ears after being struck by the baseball off the bat of Ian Stewart as Street warmed up in right field. Street also complained of pain down his right leg and stomach discomfort.
"Right on the pelvis. You could see a black-and-blue mark," Dugger said. "He'd hold his breath when he felt discomfort and pain."
Stewart went into the right field corner to check on his teammate soon after the incident.
"I was hoping it wasn't going to hit anybody. I thought it hit him in the arm," Stewart said. "I saw him down there and told him I was sorry. He said, 'At least you hit the ball hard.' It's just one of those trends that continues for us so far this year."
The Rockies have been hit hard by injuries this season. But they were looking on the bright side Tuesday, especially after a woeful road trip.
After all, they were getting Tulowitzki back.
The slick-fielding shortstop was activated after missing nearly six weeks with a broken left wrist. At first, the Rockies didn't miss their best player, going 15-7 without him.
But they went 2-9 on a brutal three-city trip after the break that dropped Colorado eight games behind NL West leader San Diego.
With their leader's return, the Rockies were hoping this would be the spark to get them rolling again.
"Getting Tulo back, we're expecting a lot of good things," said Clint Barmes, who will shift from shortstop back to second base and platoon with Jonathan Herrera. "Having him back in our lineup is only going to make us stronger, is only going to make us better. I don't know if you want to say savior or not, but it's pretty important for us to have him back."
No pressure there.
"That's what everyone thinks is going to happen: Since I'm coming back, all of a sudden something magical is going to happen -- we're going to win all kinds of games," said Tulowitzki, who broke his wrist June 17 in Minnesota when he was hit by a pitch from Twins reliever Alex Burnett. "The reality of it is that's not how it's going to be. I'd like to contribute, but at the same time, I'm not no savior. I'm not going to turn this thing by myself."
To make room for Tulowitzki on the roster, the team designated first baseman Brad Eldred for assignment. He was hitting .250 as he helped fill in for Todd Helton, who's been out since early July with a stiff lower back.
Rockies manager Jim Tracy was thrilled at the thought of penciling Tulowitzki's name back into the cleanup spot. Tulowitzki entered Tuesday hitting .306 with nine homers and 34 RBIs.
"Obviously, we're putting a very special name back in the lineup," Tracy said before the game Tuesday night against Pittsburgh. "It's a very good feeling, knowing we have the opportunity to do that."
It's been an injury-riddled season for Street as the reliever missed the first 69 games of the season recovering from an inflamed right shoulder.
Since his return on June 22, Street has saved six games in seven chances. His command has been pinpoint, striking out 15 and issuing just one walk in 15 innings.
Soon after being hit, Street went to the ground in the right field corner. He had a throng of teammates gather around him as they waited for the ambulance to arrive.
"It's scary when you have to have the ambulance come out," Stewart said. "It's not something we're accustomed to out here. I said a prayer for him and hope he's OK. That's all I could do for him."