Gibson arrived with a flower in his hand and posted a photo to Instagram of himself at the scene holding a piece of the wreckage.
"I will keep your energy with me forever #AshesOfAnAngel fast family around the world we live you and we love you Paul is the heartbeat of this franchise and were gonna see to it that his energy and presence lives on forever #myhearthurtssobad," he wrote.
"My heart is hurting so bad no one can make me believe this is real Father God I pray that you send clarity over this cause I just don't understand My heart hurts it's broken no one can convince me that this is real.... Prayer warriors please pray real hard for his only child, his daughter and family... #HeartOfAnAngel13YrsFamilyForeverWeJustCelebreatedYour40thBirthday..... My God... My God... I can't believe I'm writing this."
Walker, who was 40, is survived by his 15-year-old daughter Meadow Rain.