O’FALLON, Mo. – A suspect has prompted a large police presence Saturday morning in O’Fallon.

Police say a suspect is barricaded in the 1500 block of Washington’s Crossing as of 10:30 a.m. Saturday.

The O’Fallon Police Department says the suspect is a 53-year-old man with a history of mental illness. He is believed to be the only one inside the barricaded home. Police believe he is also armed.

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The suspect lives at home with a family member, who got out safely before police response. It’s unclear what else might have led up to the situation.

Police negotiators and a SWAT team are trying to talk to the suspect in hopes he peacefully leaves the house unarmed.

Officers are asking people to stay out of the area while dealing with the situation, which has prompted an hours-long response. This is a developing story. FOX 2 will update as more information becomes available.