Tony Kanaan, Helio Castroneves OK

BALTIMORE -- IndyCar Series stars Tony Kanaan and Helio Castroneves were involved in a scary crash during the Sunday morning practice session for the inaugural Baltimore Grand Prix, but both Brazilians walked away.

Kanaan's KVRT Racing Technology-Lotus entry suffered a brake failure on the high-speed run into Turn 1 of the Baltimore street circuit. The out-of-control machine struck the back of Castroneves' slower car and was launched in the air into a series of banded tires placed to slow cars in a designated runoff area.

Both drivers will start the race in backup cars.

"Going down to Turn 1, I had no brakes," Kanaan related. "Fortunately I ended up hitting Helio. If it wasn't for him, I probably was going to be hurt, but unfortunately I took him out from a mechanical failure that we caused.

"It was frightening," he added. "Arriving at 190 mph with no brakes is definitely not fun. Helio saved my life today, I have to say. I was just disappointed because a brake failure in a racing car is something that should not happen at any time."

Castroneves said he was relieved to see his longtime friend and rival emerge unscathed.

"I just felt the impact and then I saw the undertray of a car," Castroneves stated. "He really flew, and I was very worried about it because he landed in a very bad position. When I looked he didn't move at all so I ran to make sure he was OK. I'm glad he was OK but it was a very scary accident.

"It's a shame that we were there, but the way I understand it, he lost the brakes. At least I was there to kind of like soften the crash for him because it would have been really, really bad."

Assessing the damage to his car, Castroneves said: "It's substantial. But it's mechanical. Both drivers are safe, and at the end of that day, that's what matters."

A second accident involving Ana Beatriz, JR Hildebrand and James Jakes brought a premature end to the 30-minute practice session.

John Oreovicz covers open-wheel racing for ESPN.com.