California police to investigate officer shown punching 14-year-old boy on video

• Rancho Cordova officer pinned teen to the ground
• Sheriff's office says boy was 'physically resistive'

A northern California police officer is under investigation after a video went viral that captured him punching a 14-year-old black boy that he had pinned to the ground.

The video, which was posted to Twitter by the boy's family and friends, shows an officer from Rancho Cordova, a city east of Sacramento, holding the boy in the dirt, at one point with his hand on his neck, and striking him several times in the chest.