A car was discovered in a lake behind the Naperville Police Department during a training exercise on Thursday afternoon, prompting a police investigation, authorities said.

In an alert sent through the Naper Notify Mass Notification System, Naperville police said a large police presence was visible near Lake Osborne, south of Aurora Avenue and east of Ogden Avenue.

Authorities said officers were investigating a vehicle that was found in the water during a training exercise, and there was no known threat to the public.

NBC Chicago's Sky 5 helicopter captured footage of the scene showing fire department crews using a variety of equipment and multiple divers in the water. An area surrounding the lake was also blocked off with crime scene tape.

Additional information wasn't immediately ava

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