An out-of-control car driving east on Route 22 struck three cars, knocked down fences, a telephone pole and live wires, and sent boulders crashing through storefront windows Wednesday afternoon, before it finally came to a halt in front of Sanguiliano's Garden Center and Nursery in Scotch Plains.

Police said it appears that the driver, whose name they declined to release pending further investigation, suffered a medical emergency that caused the crash. A message sent by Breaking News Network, which monitors scanner traffic, said that paramedics treated the driver for a diabetic emergency.

No other motorists suffered life-threatening injuries, police said. Witnesses to the accident said that the driver of the out-of-control vehicle was a middle-aged woman, about 45-years-old with brown hair. They said she appeared to have suffered burns or bruises to her forearms. Police said she did not live in Scotch Plains.

Following the crash, police temporarily closed about a 500-foot section of Route 22 on both the eastbound and westbound sides. The downed power lines cut power to traffic lights at the intersection with Glenside Avenue, police said, and live wires lay strewn across the highway. Traffic was diverted onto Mountain Avenue.

The crash started at about 3 p.m., Detective Lt. Brian Donnelly said in a telephone interview. The driver was traveling on Route 22, when she apparently suffered a medical problem, lost control of her vehicle and sideswiped two cars. According to witnesses, the collisions occurred in front of the Dunkin Donuts between Victor Street and Glenside Avenue.

The woman's vehicle continued speeding down the highway, and either she or another vehicle struck a utility pole, Donnelly said. "Wires came down, and the light went out," he said.

The vehicle careened across Route 22, and slammed through a palette of boulders that sat near a driveway entrance to Sanguiliano's Garden Center. The rocks, some two-feet wide, flew through the store's plate-glass windows and rained on the front sidewalk.

"It was just loud crashes," said co-owner Jennifer Sanguiliano, 39. "It was crazy, because it didn't end. She hit the cars, then the pole, then the boulders then the fence."

Sanguiliano and her sister were in the back of the store. Her brother said he was outside. When they heard the collision, they all came running.

Out front, they found the woman's car. It had finally stopped, a chain-link fence, potted plants and splintered wood from the utility pole trapped beneath its wheels. Another vehicle, parked in the Sanguiliano lot, had also been struck.

The driver's side airbag of the out-of-control vehicle had deployed. The driver, whose forearms had turned black with either burns or bruises, Sanguiliano said, appeared to be in shock.

"She kept looking at her arms. She couldn't talk." Sanguiliano said. "She was getting out of the car, and we told her to stay there."

Scotch Plains police, fire and medical units arrived within minutes. PSE&G and the  New Jersey Department of Transportation also sent responders, who helped cleared the downed power lines and debris. The Scotch Plains Department of Public Works assisted with cleanup.

The accident is still undergoing investigation, Donnelly said. As of 4:45 p.m., traffic appeared to be moving on both sides of Route 22 in the area around the Glenside Avenue intersection.