MIDDLESEX COUNTY, ONT. -- The arrest of a man who allegedly threatened someone with a hatchet has resulted in Ontario's Special Investigations Unit being called in.

St. Thomas police officers, along with the Canine Unit, tracked the man to a gully shortly after an incident around 10 a.m. on Sunday.

Investigators say he had threatened a 40-year-old man with a hatchet in the area of Hincks and Centre streets.

When police found him, he was reportedly combative, but was eventually arrested.

Once in custody, police say he was found to have an injury and was taken to hospital where he was treated and released.

No details have been released on the nature or severity of the injury, but due to that injury, the Special Investigations Unit is now involved.

No one else was hurt in the altercation.

The 57-year-old St. Thomas man has been charged with assault with a weapon, resisting arrest and possession of stolen property.

Anyone who may have witnessed the alleged threatening incident is asked to contact police at 519-631-1224 or Crime Stoppers at 1-800-222-TIPS.