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A man armed with an AK-47 pistol and wearing a ski mask was arrested on Monday just blocks from Fiserv Forum, where the Republican National Convention (RNC) is being held in Milwaukee, a federal law enforcement source confirmed to Fox News.

Homeland Security Investigators and Capitol Police were conducting surveillance near the RNC perimeter when they noticed a suspicious man approaching. He was wearing a ski mask and carrying a tactical bag, Fox News’ source confirmed. 

Inside the bag, police found the gun and a full magazine. His intentions were unclear.

Milwaukee Police confirmed the incident to Fox News, saying a 21-year-old man, now identified as Donnell Tinsley, was arrested around 1 p.m. on Monday on the 1200 block of N. 11th Street. 

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Mugshot of Donnell Tinsley, 21

A 21-year-old Donnell Tinsley of Milwaukee faces a misdemeanor charge of carrying a concealed weapon near a Republican National Convention security zone. (Milwaukee County Jail)

Police said Tinsley does not have a concealed weapon license in Wisconsin or any other state.

According to a criminal complaint obtained by FOX 6 Milwaukee, Tinsley is facing a misdemeanor charge of carrying a concealed weapon near a RNC security zone.

The complaint stated that a Homeland Security Investigations Special Agent and U.S. Capitol Police were patrolling RNC "exterior zone one" on Monday, when they spotted a man "wearing black pants, a long sleeve tan sweatshirt, black gloves, a ski mask, and carrying a large black tactical backpack."

The Special Agent then pulled up next to Tinsley and began a conversation. However, the agent noticed "Tinsley's hands shaking, and Tinsley began to look left and right,' the complaint read. 

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Large gate in downtown Milwaukee ahead of RNC

Gates, barricades and other security measures in downtown Milwaukee ahead of the RNC. (Fox News)

The agent then noticed a bulge in the defendant's waist band, which prompted the agent to ask TInsley if he had a firearm. The report said Tinsley told the agent he did not have a gun and that, "You can check me, go ahead and look."

After a pat down of Tinsley, the complaint said Tinsley consented to a search of his backpack. When the agent opened the bag, he immediately spotted a "concealed AK-47 pistol in the backpack," the complaint says. The Special Agent asked the defendant if he had a concealed carry permit, and Tinsley stated he did not. Tinsley was then taken into custody.

He is currently being held in the Milwaukee County Jail on a $500 bond and charges are pending. 

Fox News reached out to the Secret Service about the incident and was referred to Milwaukee Police. Fox News also reached out to Homeland Security Investigations and the Department of Homeland Security, but has not yet heard back.

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This is not the only disturbing security concern to take place at the RNC. On Tuesday, a man was shot and killed by police about two miles from Fiserv Forum. A witness told Fox News the man lived in a nearby homeless camp and was brandishing a knife when he was shot.

Also on Tuesday, Rep. Derrick Van Orden, R-Wis., said he was assaulted by a protester. He said a member of CODEPINK assaulted him while he was waiting in line to enter the venue. He called it an "incident of political violence."

CODEPINK said the woman "was intentionally bumped into by this bald, white member of Congress while he tried to shove past her." The activist group denied Orden was assaulted.

This all comes as Tuesday’s theme of the RNC is "Make America Safe Once Again" and former President Trump has called to address crime in Milwaukee.