One week after dirt track racer Kevin Ward Jr. was killed when he was struck by a car driven by Tony Stewart, Stewart’s camp says the NASCAR star is grieving and trying to deal with the tragedy.

“It’s been an emotional week for him,’’ Brett Frood, executive vice president at Stewart-Haas Racing, said during a news conference Friday at Michigan International Speedway, where it was announced veteran Jeff Burton would drive for Stewart in Sunday’s Pure Michigan 400.

“He’s grieving,” Frood said of Stewart, whose role in the fatality led NASCAR to announce Friday a new rule barring its drivers from approaching the track or moving cars after an incident during a race. Stewart could face criminal charges, although no charges are currently pending.

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The new rule takes effect immediately and applies to all NASCAR series.

"Through time you have to recognize when you get a reminder or tap on the shoulder, something that may need to be addressed," said Robin Pemberton, NASCAR's vice president of competition and racing development. "This is one of those times where we look outside our sport and we look at other things, and we feel like it was time to address this."

IndyCar reviewed its safety guidelines after Ward's death, and the protocol is similar to what NASCAR announced Friday, IndyCar spokesman Mike Kitchel said. Drivers are supposed to stay put until a safety team arrives unless there is a fire or other extenuating circumstances.

It remains to be seen how NASCAR will enforce its provision, and how much the threat of penalties will deter drivers in the heat of the moment.

Last Saturday, Stewart's car struck Ward, 20, during a sprint car race in Canandaigua, N.Y. After Stewart's car appeared to clip Ward's car, sending it spinning, Ward left the car during the caution period, walked down the track and was hit by Stewart. His funeral was Thursday.

NASCAR has thrived for years, fueled in part by the larger-than-life personalities of some of its biggest stars. Six-time champion Jimmie Johnson recalls a moment early in his career, long before he became one of NASCAR’s most-respected drivers.

"I guess the one experience that comes to mind for me in Cup was maybe my rookie year at Bristol," he said. "Robby Gordon wrecked me on a re-start, and I got out and shot him the bird."

Johnson said he supports NASCAR's rule addition. The father of two also has a slightly different perspective now on his "salute" to Gordon all those years ago.

"I'm sure I picked up a few fans and lost a few fans," he said. "Now, as a parent, if my child's hero was out there shooting the bird to another ballplayer, baseball player or football player or whatever it was, I'd probably try to steer my kids away from that. So, it depends. I don't think that entertainment value should come with any safety implications. Safety is the No. 1 priority for drivers, crew members, and the officials that are out there on the race track. And if it turns a few fans off, then in my opinion, they're a fan for the wrong reason."

The Associated Press contributed to this report.