U.S. Capitol Police stopped a group of color guard Marines on Monday who were carrying their ceremonial drill rifles, according to The Hill

The Marines, who were on their way to a ceremony on Capitol Hill, were delayed at least 20 minutes on Monday while Capitol Police checked the two inoperable rifles, The Hill reported.

Eva Malecki, a spokeswoman for the Capitol Police, said "it is a long-standing standard operating procedure for the U.S. Capitol Police to inspect all weapons."

Military color guards' weapons are inspected at each event to ensure they are inert, she said.

The screening took place at the south entrance of the Cannon House Office Building, where the Marines arrived in dress blues to present the colors. According to The Hill, three Marines went inside the building while one remained at the entrance with the rifles in their carrying case.

Malecki said the process of inspecting the Marine color guard on Monday did not take any longer than usual.

After the Capitol Police determined the rifles were inoperable, the Marines were allowed to bring the mock weapons inside and perform at the ceremony, The Hill reported.

On Friday, the Capitol building went on a brief lockdown after reports of a woman with a gun, but Capitol Police gave the "all clear" without incident.

Marine Corps Times reporter Jeff Schogol contributed to this report.