According to Norwich police, Potter, 78, appeared to have a medical emergency while driving his pickup truck west on West Town Street around 4 p.m. Tuesday.

According to witnesses, Potter lost control of the pickup and the vehicle turned sharply, hitting a school bus and several other vehicles, then came to rest in the parking lot of Global Gas Station at 154 W Town Street, police said.

He was the only person injured in the crash, police said.

After fire crews extricated Potter from the vehicle, American Ambulance transported him to William W. Backus Hospital under life-threatening conditions. He died on Wednesday.

Potter’s death comes only three days after that of another local stock car racing great Michael Stefanik, who was killed at age 61 when a single-engine, single-seat plane he was flying crashed in Sterling just after taking off from the Riconn Airport just over the state line in Coventry, R.I.

Starting at Waterford Speedbowl in 1962, Potter began winning in 1966 and before it was over captured 11 championships and an estimated 140 features at Stafford, Thompson and Waterford.

In 1988, he held the Thompson and Stafford track championships simultaneously.

A model of consistency, he ran a streak of 37 straight top-six finishes at Stafford in 1994-95.

Potter retired from racing in 2000, when his brother, Wayne, had been diagnosed with brain cancer nine months before his death.

“I took care of him in the nursing home and it was sad,” Potter told the Bulletin’s Marc Allard in 2011. “I still loved auto racing, but that took a big hit on me.”

In January 2007, Potter was inducted into the New England Auto Racers Hall of Fame.

In an October 2006 column heralding the Hall of Fame selection, the Bulletin’s Peter Vander Veer quoted soon-to-be-retired Waterford Speedbowl race official Peter Zanardi as saying: “If you put Bob Potter in a race car in the middle of a tornado, he’d find a way to see his way through without getting it damaged.”

“It’s an honor just to be mentioned with some of those guys who’ve already been inducted,” Potter said of his induction. “It was tough for all of them to get in and now I’m part of that group. Many of them were friends, both on and off the track, for years. I worked hard all my life to be as good as a I could be in racing. This is very special.”

Potter retired in 1999 from Electric Boat in Groton, where he worked for 36 years, many of them as an X-ray technician, Vander Veer reported.

Vander Veer wrote that growing up in the Taftville section of Norwich, Potter’s early love for race cars was kindered by his father, Aubrey, and a car builder right up the street from where he lived, Bill Trask.

“My father was a good friend of Dick Beauguard’s (like Potter, a Waterford Speedbowl track champion), so when we went to the races, we had a personal tie,” Potter told Vander Veer. “I spent hours at Trask’s garage.”

In 2011, the then-69-year-old Potter was named the grand marshal for the 40th annual Spring Sizzler, which kicks off the racing schedule at the Stafford Motor Speedway.

“I was content being the bigger fish in the small pond,” Potter said in 2006. “Winning at Waterford, Stafford and Thompson meant so much to me. We’d spend hours doing almost all of the work on the cars.