CHICAGO (CBS) — A Dixon man under investigation for child sex abuse shot and killed his 5-year-old son Monday afternoon, before turning the gun on himself, police said.

Police said 33-year-old Robert Michaels had been barred from being alone with with his 5-year-old son, Christopher, because he was under investigation for the alleged sexual abuse of another child.

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Christopher’s mother brought their son to his father’s home on Monday, and she told police father and son went upstairs, and locked her out of the room. She then heard two gunshots, and left the house to get her phone and call 911.

Dixon Police Chief Danny Langloss said both Christopher and his father suffered gunshot wounds to the head.

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“Our hearts truly go out to the family members who have suffered this horrific tragedy. Our officers feel your pain,” Langloss said.

The chief said it was a horrific scene for officers who responded to the shooting. Those officers have been placed on short-term leave to deal with what they witnessed.

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“There’s nothing worse for our officers [than] to come into a situation like this, and see such a horrific senseless scene,” Langloss said.