Paul Walker -- Death Vigil Grows ... Hundreds of People Visit Fatal Crash Scene

Paul Walker fans have been heading to Valencia, CA in droves ... building out a massive vigil for the actor on the spot where he died.

Fans began to gather literally hours after the fatal crash on Saturday evening ... and by Sunday night, the memorial had grown exponentially ... with hundreds of flowers, candles, photos trinkets and letters.

As we previously reported, Walker's "Fast and the Furious" co-star Tyrese Gibson visited the crash scene yesterday ... and broke down crying when he arrived.