President Joe Biden on Sunday appealed for the country to “unite as one nation” after the attempted assassination of his predecessor, Donald Trump, and said he was ordering an independent security review of how such an attack could have happened.

Biden delivered short afternoon remarks from the White House after receiving a briefing on the investigation in the Situation Room. He called for a “thorough and swift” review and asked the public not to “make assumptions” about the shooter’s motives or affiliations.