A teenager was taken to the hospital with serious injuries after police said the van he was driving crashed into a Super Walmart on Post Road in Westerly.
The accident happened just after midnight Wednesday.
Police identified the driver as 18-year-old Thomas Brightman of Charlestown.
Police said the exterior and interior walls and some merchandise displays suffered damage.
Several witnesses said they saw Brightman driving erratically in the parking lot prior to striking the building.
"At this time we're interviewing witnesses and we're going to look at surveillance footage to try and determine the cause of this accident," said Sgt. James Campbell of the Westerly Police Department.
The 24-hour Walmart did close down for about an hour until the building inspector cleared it for occupancy.
No one else was hurt inside or outside the building.