A person fatally shot by law enforcement officers during a confrontation at a U.S. nuclear security site in Nevada has been identified as a 27-year-old Iowa man.

Nye County Sheriff Sharon Wehrly said Thursday that the man killed Monday was Nekiylo Dawayne Graves from Waterloo, Iowa.

Wehrly said in a video news release that a sheriff's deputy and a security officer shot Graves when he refused commands and continued to approach them following a pursuit after Graves' vehicle failed to stop at the security gate at the Nevada National Security Site.

The site is located 70 miles (112 kilometers) north of Las Vegas.

Wehrly said the FBI and the Nevada Department of Public Safety are investigating the incident and that her agency is conducting an internal affairs investigation.

Authorities say Graves was killed after he refused orders to drop a cylindrical object in his hand. It's not immediately clear if the object was a weapon.

(Copyright 2019 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)