Walmart has removed gun and ammunition displays from thousands of U.S. stores, citing concerns of “civil unrest.”

The world’s largest retailer said Thursday that customers can continue to purchase guns and ammunition by request. Walmart currently sells firearms at about half of its 4,700 U.S. stores.

“We have seen some isolated civil unrest and as we have done on several occasions over the last few years, we have moved our firearms and ammunition off the sales floor as a precaution for the safety of our associates and customers,” spokesman Kory Lundberg said in a statement on Thursday.

The Wall Street Journal originally reported the news.

The company did not specify the incidents to which it was referring. But according to local media in Philadelphia, at least one Walmart store was ransacked after rioting broke out after the police shooting of Walter Wallace Jr., a Black man whose family said he was in the midst of a mental health crisis.

Walmart took similar measures in June after the police killing of George Floyd in Minneapolis sparked widespread protests around the country.

Gun sales have long been a hot-button issue for the Bentonville, Ark.-based retailer. Walmart stopped selling handguns and certain types of ammunition last September, after shootings at company stores left at least 24 people dead. It also began prohibiting customers from openly carrying firearms in its stores.

“It’s clear to us that the status quo is unacceptable,” CEO Doug McMillon said in a memo to employees at the time. “We know these decisions will inconvenience some of our customers, and we hope they will understand.”