PORTLAND, Ore. (AP) - An Oregon man has filed a lawsuit claiming Dick's Sporting Goods and Walmart discriminated against him when they refused to sell the 20-year-old a rifle.

Dick's and Walmart restricted gun sales to adults 21 and older in the wake of the Feb. 14 Florida high school massacre. The 19-year-old accused in the school slaying bought the AR-15 used in the attack legally.

Oregon law allows residents to buy shotguns or rifles starting at age 18.

The Oregonian/OregonLive reports Tyler Watson's lawsuit filed Monday claims he faced age discrimination from Dick's and Walmart in southern Oregon . The lawsuit is believed to be the first filed over the new gun policies.

Watson's attorney said it's a clear case of age discrimination.

"The legislature has made a decision that they’re not going to allow private businesses to discriminate on the basis of certain protected characteristics and one of those is age," said Max Whittington.

Walmart spokesman Randy Hargrove says the retailer will defend its new policy. A representative from Dick's hasn't responded to a request for comment.