"One subject was armed with a loaded AR-15 rifle slung over his shoulder and the other was armed with a .45 caliber semi-automatic pistol tucked in his waistband," Arapahoe County Sheriff Grayson Robinson said.

Brian Laro, who lives in the same complex as Najibullah Zazi, was arrested just after 1 a.m Saturday and taken into custody for investigation of prohibited use of a weapon and disorderly conduct.

Laro, 37, appeared to be intoxicated and had a blood alcohol level of .123, Robinson said. The second man with the pistol, 24-year-old Timothy Guinn, had a blood alcohol level of .020. The third man did not have a weapon and was not arrested. He has not been identified.

"The three stated they were at Laro's apartment having a few beers when they heard what they thought was a gunshot and went to investigate," said Robinson.

Laro and Zazi both live at Vistas at Saddle Rock Apartments, which has been under FBI surveillance for days, if not weeks. Zazi's home was raided earlier this week and two of the three buildings at the apartment complex were evacuated as a precaution.

Laro was held at the Arapahoe County Sheriff’s Office Detentions Facility on a $750 bond. He was released Saturday afternoon.

Guinn was released at the scene and his concealed weapons permit was confiscated pending a review of the incident.

Robinson said the arrest is not related to the terror investigation.