ENCINITAS, Calif. -- An 11-year-old boy struck by a car more than two weeks ago while he was riding an electric bike has died, according to the Medical Examiner's Office.

Robert Franklin Thompson died at 3:30 p.m. Friday at Rady Children's Hospital, where he has been on life support since the May 6 accident, a Medical Examiner's Office report states.

Robert was on a motorized "pocket bike" and was crossing the 1000 block of Double LL Ranch Road, which is a gated, private road in Olivenhain, when he was struck by a car, according to a San Diego sheriff's report.

An electric pocket bike looks like a small scooter and can reach speeds up to 15 mph. Witnesses told deputies that the boy was coming out of a driveway and went directly into the path of the car driving down the private street.

The boy was transported by Mercy Air to Children's Hospital, where doctors subsequently pronounced him brain dead, the sheriff's report states.

The sheriff's department is investigating the accident. There were no preliminary indications that excessive speed or alcohol played a part in the collision, according to the sheriff's report.