Walker's Facebook page has confirmed his death.
The reports say Walker, 40, was a passenger in a vehicle driving in southern California when it crashed into a tree.
The car reportedly burst into flames, killing both Walker and the unidentified driver.
Some have taken to Twitter to post photos from the scene.
One person tweeted what they said was the last photo of Walker.
Last photo of Paul Walker pic.twitter.com/830aUZBfAe— Sampah Remaja (@SampahRemajaKL) December 1, 2013
The crash apparently occurred Saturday afternoon in the town of Santa Clarita.
Celebrity gossip site TMZ also posted a photo that showed plumes of black smoke billowing from what looks like the curb of an empty street.
Friends and colleagues of Walker also took to Twitter to express their grief at the news.
Please everyone go with #RIPPaulWalker P.s. Thanks you so much all!— Vin Diesel (@OffVinDiesel) December 1, 2013
"Time is long but life is short" #rippaulwalker— Ryan Seacrest (@RyanSeacrest) December 1, 2013
My heart is hurting so bad no one can make me believe this is real Father God I pray that you send… http://t.co/CnKblb3PWu— Vision Implementer (@Tyrese) December 1, 2013
RIP Paul Walker— Justin Bieber (@justinbieber) December 1, 2013
Your humble spirit was felt from the start, wherever you blessed your presence you always left a mark,… http://t.co/nUiPPIU9Bb— Ludacris (@Ludacris) December 1, 2013
We will have more on the accident and Walker's death as information becomes available.