Republican U.S. presidential candidate Donald Trump speaks at a rally in Sparks, Nevada, October 29, 2015. Reuters/James Glover II LAS VEGAS (AP) — A federal officer says a man arrested at a Donald Trump rally in Las Vegas told authorities he tried to grab an officer's gun so he could kill the candidate.

A complaint filed Monday in U.S. District Court in Nevada charges Michael Steven Sandford with an act of violence on restricted grounds.

It cites a report by Special Agent Swierkowski, whose first name was not included, saying Sandford told officers he drove from California to kill Trump and went to a Las Vegas gun range the day before to learn to shoot.

Sandford later went to a Trump rally at the Treasure Island Casino and approached a Las Vegas police officer to say he wanted an autograph from Trump.