Police in Delaware have a warning to Pennsylvania residents looking to make an alcohol run: Don’t cross the border to buy booze or for other nonessential reasons.

At Total Wine & More in Claymont, just south of the Pennsylvania border, police on Friday were turning away customers from Pennsylvania, where liquor stores remain closed and online sales have been plagued with problems due to “overwhelming demand.”

Many would-be customers seemed unaware of travel restrictions put in place by Gov. John Carney this week, which prohibit out-of-state drivers from entering Delaware unless they work for an essential business, are caring for a family member, or there are health-care reasons.

To enforce the restrictions, Delaware state police have been authorized to stop out-of-state drivers on state and local roads simply because they don’t have Delaware tags. Residents from Pennsylvania and elsewhere who don’t have a good reason to be in the state are being instructed to either self-quarantine in Delaware for 14 days or return home. Some Pennsylvania customers were also turned away from a Home Depot by Delaware state police on Friday.

The order doesn’t apply to motorists passing through Delaware en route to other states, and out-of-state drivers on I-95, I-295, and I-495 won’t be stopped. Police aren’t just stopping Pennsylvania drivers — Maryland drivers are also passing over the state’s western border, according to Master Cpl. Michael Austin, a spokesperson for the Delaware State Police.

“We’re going to have to show we’re serious about travelers coming in state for nonessential activities,” Carney said during a news briefing on Friday.

Pritiss Gupta, co-owner of Brandywine Liquors, said he’d seen an increase of sales in recent weeks, with many customers from Pennsylvania thanking him for remaining open. Managers at other liquor stores in the area said they’ve seen an uptick in sales, but couldn’t say for sure if it was due to an increase in Pennsylvania customers.

“We have also been getting phone calls asking if we’re open,” Gupta said. “I would like to help customers get their products."

In the days before Pennsylvania’s liquor stores closed in compliance with Gov. Tom Wolf’s nonessential business shutdown, statewide alcohol sales shot up by more than 58%, according to the Liquor Control Board.

» READ MORE: What’s allowed to be open in Pa.? Here are the ‘life-sustaining’ businesses.

Delaware classified liquor stores as an essential business out of fear that suddenly cutting people off could cause more crowding in hospitals, according to Carney.

“If you close liquor stores, you have people who are alcohol dependent who will go through withdrawal and end up in my emergency room, and we don’t want to have that," Carney said.