This is the dramatic moment when a cop had to physically wrestle one of Paul Walker's friends away from the crash scene ... seconds after it became clear Paul could not be saved.
TMZ broke the story ... Paul's friends rushed to the scene -- one even grabbed a fire extinguisher and desperately tried to extinguish the flames.
When the fire dept. arrived they tried to pull Paul's friends away. One of Paul's longtime friends, a guy named Nute, was so overwrought with emotion, he punched a firefighter. We're told Sheriff's deputies put Nute -- and several other of Paul's friends -- in custody, but let them go when they realized the circumstances.
Cops now believe Paul and the driver of the Porsche may have been in a street race with another car at the time of the crash and are looking for footage and witnesses.