Bruce Jenner -- She Slammed On Her Brakes ... I Didn't Have a Chance

Bruce Jenner told cops the Lexus driver who was killed in Saturday's crash suddenly, without warning, slammed her brakes in front of him and there was no way he could avoid the crash.

Multiple sources tell us ... Bruce couldn't say if the Lexus driver had smashed into the Prius before his SUV struck her car, because it all happened so quickly.

Law enforcement sources tell us ... the Lexus left no skid marks, but that is not necessarily telling. Bruce's SUV didn't leave skid marks either ... only his trailer did. We're told the anti-lock devices on these vehicles could have prevented the tires from skidding.

Bruce's problem ... drivers are supposed to leave enough space between themselves and the car in front to prevent such accidents, and this is consistent with what law enforcement believes ... that Bruce was following too closely.

Our law enforcement sources tell us they have not drawn any conclusions, but the scenario that the Lexus did not hit the Prius but that Bruce did after pushing the Lexus into oncoming traffic is still in play.