NASHVILLE, Tenn. (WKRN) – An investigation is underway after someone set a backpack on fire at Riverfront Park late Thursday night.

It happened around 11:45 p.m.

Metro police told News 2 a man was walking his dog when he noticed someone sitting on the steps, talking to himself and yelling.

The man ran off just before the dog walker heard what he thought was an explosion and called 911.

Officers located a burned backpack but there was no sign of an explosion.

The Hazardous Devices Unit was called to the scene as a precaution and determined nothing exploded.

The Nashville Fire Department is investigating the incident as arson but no property other than the backpack was damaged.

No additional information was released.