Michael Dyer was riding his bike in the area when he heard and saw the moment the chopper went down on Jan. 26.
He said he was just a few feet away and captured the smoke and flames coming from the scattered debris.
Dyer told Bike Magazine he watched the helicopter go very fast and fly very low right before it hit the hillside.
Kobe Bryant death: No engine failure in helicopter crash, preliminary NTSB report says
The National Transportation Safety Board has not released its final report but investigators believe poor weather conditions and pilot error are likely causes of the crash.
A preliminary report from the agency released Friday said there is no evidence of engine failure in the helicopter crash.
The group was flying to a girls basketball tournament at Bryant's Mamba Sports Academy. Gianna's team was coached by Bryant and was playing in the tournament.
A public memorial for Orange Coast College baseball coach John Altobelli, his wife, Keri, and daughter Alyssa was held Monday at Angel Stadium. Also killed in the crash were pilot Ara Zobayan and Bryant friends Christina Mauser, Sarah Chester and her daughter Payton.
Staples Center will host a memorial for Bryant and his daughter Gianna on Feb. 24.
Kobe honored by mariachis with emotional rendition of 'Amor Eterno' outside Staples Center