CHICAGO — Officials gave an ‘all clear’ Sunday night after a Chicago police SWAT team responded to Northwestern Memorial Hospital for an ‘active intruder threat.’

Per a spokesman, hospital security, Northwestern police and CPD responded and conducted an active sweep of the building and determined no active threat.

The hospital has resumed normal operations after being placed on lockdown while authorities investigated.

Before the ‘all clear,’ a heavy police presence lined the 200 block of W. Huron in Streeterville.

A man who arrived at the hospital to visit a friend says he and about 20 others were quickly ushered away by staff.

“So we were hiding, sheltering in place as it were, and it’s just very scary because you don’t know what is going on,” said Gregory O’Laughlin. “You see armed security. Armed police. Armed officers with riot shields and everything, trying to keep everything secure, and it’s just very scary.”

O’Laughlin adds that he saw several people in need of medical attention.

The hospital spokesperson adds that the threat came in as an outside call and an investigation is underway.