Brendan Schaub -- former UFC star and comedian -- saved 3 children from a terrifying car wreck last week ... after their father allegedly drove the wrong way on the highway, killing the kid's mom in a fatal collision.
38-year-old Schaub was driving to a restaurant with his girlfriend on August 12 around 7 PM... when he saw an 18-wheeler and a mangled 2003 Lincoln were involved in a serious accident.
Schaub says he saw a child sitting on top of the vehicle, screaming for assistance ... so he pulled over and immediately sprang into action, rushing to the car to help.
According to docs, the man -- who was not seriously injured in either of the crashes -- was combative with cops, according to law enforcement, and had to be tased.
Thankfully, the children only suffered minor injuries.
The family of the deceased mom has started a GoFundMe-- already over $46k -- to raise money for a funeral.
"My niece Aimee García (26) was Killed In Wrong-Way Driving Collision With Big Rig On 101 Freeway In Encino. She leaves behind four beautiful children all under the age of 8," the fundraiser profile reads.
"She was a loving, caring mother unfortunately she was a victim of domestic violence for many years and yesterday the aggressor fulfilled his objective and enter the freeway the wrong way intentionally killing my niece. Thank God the children are fine but very traumatized."
Schaub was one of the best heavyweights in the world as a fighter ... beating guys like Matt Mitrione in the UFC.