Fageh Behbahani, 49, was driving an Ohio couple from SFO into the city to their hotel when his Desoto cab caught fire and slammed into a concrete pillar on the Mariposa Street off-ramp from I-280.
Behbahani told investigators he smelled smoke two miles before the crash took place and that his brakes failed right before the crash.
CHP investigators say they are determining if he broke the law by not pulling over right away.
The couple has been identified as Dennis and Karen Marshal of Cincinnati.