Hawaii County police say a 63-year-old Hilo man died today following his arrest for drunken driving after the man crashed his motorcycle into the back of a car.

Police said the man was thrown from his motorcycle when he rear-ended a car on Makaala Street at 3:10 p.m. Saturday. They said the man refused medical treatment and officers took him into custody for operating a vehicle while under the influence of an intoxicant and driving without a license or insurance.

The man was not able to post $1,250 bail so police said officers placed him in a cell by himself. They found him unresponsive in the cell at 10:20 p.m. and called for an ambulance which took the man to Hilo Medical Center.

A doctor at the hospital pronounced the man dead at 4:40 a.m. today.

Police say they have classified the case as an unattended death and have assigned it to the Hawaii Police Department’s Criminal Investigations Section. The department’s internal affairs division also will conduct an administrative investigation to determine whether or not officers followed department policies and procedures.

Officials have ordered an autopsy to determine the cause of the man’s death. They are withholding his name pending notification of family members.