PHOENIX -- Police have arrested a man who they say sexually assaulted a 4 year old girl at a playground at University Park.

Police say the girl was at the playground with her family near by. Several witnesses say they saw suspect William Speed grab the girl while she played on the jungle gym and begin sexually assaulting her.

The girl screamed and her family had to fight Speed to get him off of the girl. The family and nearby witnesses restrained Speed until police arrived.

Suspect William Speed is a Level 3 sex offender. He was booked into jail for sexual conduct with a minor.

Phoenix Police

William Speed, Level 3 sex offender.