UPDATE: The two people shot at Navy Pier have died, officials said. Police are now searching for a person of interest they believe is a "disgruntled ex-employee." Read more here.
Two people were shot at Chicago's popular Navy Pier attraction Tuesday, fire officials confirmed to NBC Chicago as the pier urged anyone inside to shelter in place.
The shooting happened sometime before 1:45 p.m. in the 900 block of East Grand, according to Chicago fire officials. The exact location of the shooting and details of circumstances surrounding it were not immediately known.
Fire officials said at least two people were shot and critically wounded. Further details on the victims weren't released.
Navy Pier asked everyone at the venue to shelter in place while police investigated.
“Due to an active incident under investigation, we are asking everyone to shelter in place until given the all-clear by CPD," Navy Pier said in a statement.
Some in nearby offices and buildings were also told to remain inside or "use extreme caution" amid the investigation.
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A large police presence was visible at the scene, footage showed.
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Some who were inside Navy Pier at the time of the incident reported seeing police arrive at the scene, unaware of what was happening.
"Initially one police officer SUV showed up first, didn't think much of it ... then he hops out and there was two officers... immediately pulled out automatic weapons, SWAT gear, the works," said Trent Halasek of Cincinnati, who was visiting the pier during a business trip at the time.
Check back for more on this developing story.