Wisconsin Sen. Ron Johnson on Sunday did not shy away from describing an overnight shooting that left 50 dead in Orlando, Fla. a “terror attack.”

“My committee will work to support the federal role in investigating this terror attack and protecting against further threats,” Johnson, chairman of the Senate Homeland Security and Governmental Affairs Committee, said in a statement.

“As Americans we must unite to defeat terrorism’s threat to our nation’s security,” he added.

Local law enforcement authorities noted during a press conference Sunday morning that the shooter, Omar Mateen, was an American-born citizen whose parents immigrated to the U.S. from Afghanistan. FBI officials have indicated they have reason to believe Mateen “may have [had] leanings towards” Islamic extremism.