The man, who was not identified by name, had acted aggressively toward two agents before one officer opened fire during the incident in Sumas, Washington, according to the US Customs and Border Protection.
He was later found to be carrying a hatchet in his backpack and was wanted on a murder charge, Whatcom Sheriff Bill Elfo told a news conference on Friday. He did not say where the homicide occurred, and the man's nationality has not been made public.
The Department of Homeland Security Inspector General, Customs and Border Protection internal affairs and other authorities were investigating the incident, and details have also been sent to the FBI.