Update 7 p.m. : Police issued an "all clear" Tuesday afternoon, four hours after investigating a report of a man with a gun on campus at a university in Indianapolis, the school said on its emergency management Twitter feed, as reported by Reuters.

An alert from Indiana University-Purdue University Indianapolis had advised students and employees to remain in a "shelter location" until the "all clear" notice was received. Normal operations and scheduled evening classes are being held.

The university had originally reported a "man with a long gun" seen in a parking lot, and urged students to seek shelter.

The IUPUI campus was under lockdown as authorities investigated reports of a gunman at the school.

“#IUPUI is still on full alert. Police continue to search campus for potential armed individual. We will continue to share all info we have..,” the university posted on its Twitter account at 3:48 p.m. Tuesday local time.

The school reiterated the alert at 4:11 p.m.

"#IUPUI campus remains on full alert," the school said. "Thank you for your patience, everyone. We realize this is frustrating, but it is necessary for safety."

A female student reported seeing a man wearing a long brown coat and carrying a rifle or shotgun near IUPUI’s medical school around 12:30 p.m. Tuesday, Campus Police Capt. Bill Abston told the Associated Press. Similar reports also trickled in.

Students and staff on the university’s downtown campus were told to seek shelter as campus police and Indianapolis Metro police investigated reports of a gunman, according to the AP. University Hospital and Riley Hospital for Children, both affiliated with IUPUI, were under lockdown.

"It's very challenging when we get something like this. There are a lot of main streets in and out and a lot of people," Abston told the AP.

Police plan to search all campus buildings and the parking lot, Abston said. The female student lost sight of the gunman and authorities weren’t sure if he left the campus or not.

Dan Engling, a 23-year-old IUPUI student, wasn’t alarmed over the situation.

"It's kind of breaking up the monotony, people think it's interesting," he told the AP.

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