FILE PHOTO: A customer walks out of a Walgreens pharmacy store in Austin, TX, U.S., March 26, 2018. REUTERS/Mohammad Khursheed

(Reuters) - Walgreens Boots Alliance Inc WBA.N, CVS Health Corp CVS.N and supermarket chain Wegmans Food Markets Inc said on Thursday they would start asking customers to not openly carry firearms in their stores, joining Walmart Inc WMT.N and Kroger Co KR.N, in a change of gun policy following several deadly mass shootings in the United States.

The retailers are among a growing number of U.S. companies, such as Delta Air Lines DAL.N and Bank of America BAC.N, that are responding to calls for action to help curtail the rash of gun violence that has plagued the nation, risking backlash from powerful gun owners' groups as politicians consider options.

“We are joining other retailers in asking our customers to no longer openly carry firearms into our stores other than authorized law enforcement officials,” Walgreens said in an emailed statement.

Earlier this week, Walmart and Kroger said they would ask shoppers to stop openly carrying firearms in stores across the United States. Walmart also said it would discontinue sales of ammunition for handguns and some assault-style rifles in U.S. stores, and called for action on gun safety after a string of mass shootings, including at Walmart stores in Texas and Mississippi.

"There's nothing more important than the safety of our customers & employees," Wegmans said in a tweet on Thursday, adding that it "prefers" that customers not openly carry firearms into its stores. (bit.ly/2lyaafV)

CVS Health echoed the sentiment saying, “We join a growing chorus of businesses in requesting that our customers, other than authorized law enforcement personnel, do not bring firearms into our stores.”

As the chains began making their announcements on Thursday, Shannon Watts, founder of gun control advocacy group Moms Demand Action said, “We hope Senate leaders are watching this sea change.”

“We’ll take this momentum to Washington when Congress is back from recess on Monday.”

The Democrat-controlled House of Representatives passed a bill intended to close loopholes around background checks for gun purchases and other measures in February, but it has not been taken up by the Republican-led Senate.