Hazardous materials crews were called to the Walmart Store Tuesday afternoon along Routes 209 and 6 in Westfall Township, Pike County.
Witnesses near the scene said the store, which is between Matamoras and Milford, was evacuated.
Officials said a white powder was found on the floor near the self check-out at the front of the store. The powder has not been identified.
There were no reports of any injuries.
The store reopened several hours later.