The University of Colorado Boulder's campus issued a campus-wide shelter-in-place near the Norlin Library. Police evacuated the library and Sewell Hall and said they responded to a call of shots fired, but hadn't found anyone injured.

The alert was sent to the CU community at 4:54 p.m. and said, "Emergency personnel responding. Avoid area."

The university later said around 5:15 p.m. that the shelter-in-place remains in effect for the main campus and the East Campus is not impacted.

A 2011 Getty Images file photo shows the main entrance and plaza of the Norlin Library in the center of the University of Colorado, Boulder campus. Getty Images

"CUPD and Boulder Police are responding to a call near the Norlin Library on main campus," the university said in an alert. "CUPD is evacuating No

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