A 25-year-old congressional summer intern from Kansas was arrested Monday morning after police said he tried to enter the Longworth House Office Building with an unloaded handgun.

Joshua Wheeler, an intern for Rep. Lynn Jenkins (R-Kan.), was charged with carrying a pistol without a license and possession of an unregistered firearm. He was being processed by police late Monday morning.

Tom Brandt, a spokesman for Jenkins, who is vice chair of the House Republican Conference, said Wheeler has been put on temporary leave. “We are cooperating with Capitol police,” Brandt said. “Our current understanding is that this was an accident.”

Lt. Kimberly Schneider, a spokeswoman for the U.S. Capitol Police, said the gun was discovered when Wheeler, who is from Atchison, Kan., was searched at the entrance on New Jersey Avenue and C Street Southeast. She said the gun was a 9mm Smith & Wesson.