Ottawa police have charged a 50-year-old man in relation to a downtown robbery that prompted a large police operation and shut down the Rideau Centre mall.

Police say the man entered a business inside the shopping mall and when he was confronted by security, he brandished a firearm. He was arrested "a short distance away," police said in a release. No one was injured.

Carlos Smythe has been charged with robbery and several firearms-related offences. Police say "there are no further safety concerns" related to the incident.

On Tuesday, officers with guns drawn could be seen outside the mall, including near the entrance to the Rideau transit station shortly after noon. Heavily armed tactical officers could be seen entering a mall entrance on Rideau Street.

Police urged people to avoid the area. A message sent to employees said the building was locked down due to an emergency.

Employees who hadn't been evacuated were instructed to lock down within stores and stay away from the doors. A later message to mall tenants said police would be sweeping the mall floor-by-floor and store-by-store.

The mall reopened later Tuesday afternoon.

"The police operation is now over but the investigation is ongoing," Ottawa police tweeted just after 3:30 p.m. A spokesperson for Cadillac Fairview, the mall's owner, said that the mall is again open for business.

"The Ottawa police have completed their onsite investigation and CF Rideau centre is now open for the remainder of the day," the statement said.Police earlier tweeted they responded to a shoplifting call with a "possible weapon," that one person was arrested and there was no threat to public safety, but then deleted the tweet.

Mall employee Duran Mohamed was inside when police arrived early Tuesday afternoon.

"All of a sudden I hear security just yelling, trying to get everybody to evacuate the store," he said. Police then came into his store telling customers to leave, he said.

Several witnesses earlier reported the power went out inside the shopping centre. Customers just inside an entrance on Rideau Street were told to leave and run west, toward Sussex Drive soon after police arrived.

Ottawa's LRT service was suspended between uOttawa and Parliament stations, but has since resumed.

It's the mall's first day open in more than three weeks. It closed during the 'Freedom Convoy' occupation of downtown Ottawa, causing employees to lose wages and stores to lose revenue.

"I just feel so sorry for the poor employees at the mall," said Julia Niblock, who was shopping at nearby Hudson's Bay. "It’s their first day reopening and it’s what, two hours before this happens? So my sympathies are really more with them.”

with files from Matt Skube, CTV News Ottawa