More details emerging in the car crash that killed the wife of OKC Thunder assistant coach Monty Williams -- with cops telling TMZ Sports they believe the other car was speeding at the time of the accident.
Ingrid Williams died Wednesday morning ... hours after her car was struck head-on near downtown Oklahoma City by a car going the opposite direction that veered across the median. The other driver was also killed in the wreck.
Now, a rep for the OKC Police Dept. tells us speed appears to have been a factor -- "The other driver was clearly going at a fast rate of speed. It was really fast."
The other driver also had her dog in her lap at the time of the crash -- leaving many people wondering if the pet distracted the driver on the road.
"I don't know if we'll ever know [if the dog was a factor]. She was in the car by herself."
We're told investigators will be testing blood from both drivers to see if alcohol or drugs were involved (standard operating procedure in cases like this) but results won't be back for at least another week.