The FBI fears the deadly weekend of mass shootings could inspire more massacres — with an alleged copycat already arrested in Florida.

“The FBI remains concerned that U.S.-based domestic violent extremists could become inspired by these and previous high-profile attacks to engage in similar acts of violence,” the bureau said in a statement Sunday.

“The FBI asks the American public to report to law enforcement any suspicious activity that is observed either in person or online.”

The bureau said the attacks Saturday in El Paso, Texas, and Sunday in Dayton, Ohio — killing a total of 31 — “underscores the continued threat posed by domestic violent extremists and perpetrators of hate crimes.”

FBI Director Chris Wray has ordered all of the agency’s offices to conduct a new threat assessment to try to thwart future attacks, law enforcement sources told CNN.

The fears appeared to come true swiftly when on Sunday, a Florida man who was arrested for threatening to “shoot up” his local Walmart said he’d been “intrigued” by the weekend’s double massacres, according to cops.

Wayne Lee Padgett, 31, is accused of targeting a Walmart in Gibsonton, 10 miles south of Tampa, calling the store to warn he was coming.

“He was intrigued with the shootings over the last couple of days,” Hillsborough County Sheriff Chad Chronister said at a press conference.

“After the events over the last week, we all fear for our safety to begin with, so to have an individual who for whatever reason wants to be a copycat, or wants to [instill] fear in people for whatever that motive may be is disturbing,” Chronister said.

FBI officials recently told a congressional hearing that the bureau is investigating nearly 850 people as possible domestic terrorists, according to the Washington Post.

“We, the FBI, don’t investigate ideology, no matter how repugnant,” Wray said at the hearings. “When it turns to violence, we’re all over it.”