Updated 1:45 p.m. Monday.

Update: The Greenfield Police Department has identified the victim in the crash as 20-year-old Robert Hassler.

Police said that Hassler was in "grave condition" as of Monday morning, though one poster on the Support Robert Hassler Jr's Battle/Recover Facebook page indicated he had "showed improvement" today as he recovers from head trauma.

Original story, posted at 3:30 p.m. Nov. 23: The Greenfield Police Department is investigating a motorcycle crash that occurred Wednesday afternoon in the 5000 block of South 116th Street, near Whitnall High School and Whitnall Middle School.

According to police, units responded to the single-vehicle crash at approximately 1:20 p.m.

A 20-year-old male Greenfield resident was the operator and sole rider of a motorcycle that was traveling northbound on South 116th Street. The operator, who was not wearing a helment, lost control of the motorcycle, left the roadway and crashed. He sustained severe head injuries and was transported to Froedtert hospital by ambulance.

The initial investigation and witness statements indicate the operator was traveling at a high rate of speed and attempting a stunt when he lost control. It is unknown if alcohol is a factor at this time.