SAN ANTONIO -- A witness spoke out on Monday, after seeing a deadly crash involving a San Antonio police officer.

Rosita Davila, 64, was killed on Sunday when her Jeep collided with a Chevy Impala, driven by San Antonio police Sgt. Gabe Trevino.

The accident happened around midnight on Loop 1604 between Stone Oak Parkway and Highway 281.

Ben Jimenez told KSAT 12 on Monday that he was driving home when he saw the accident.

"That's when I saw the car flipping," said Jimenez. "I didn't see nobody in front of it, but I saw a car pass it."

Jimenez said he pulled over, called 911 and tried to help the two women in the Jeep. He said both women were hurt, especially the driver and that it was the worst accident he has ever seen.

"The ditch ... actually goes pretty far down and the Jeep must have been flipping so hard, it actually flipped over the concrete wall," said Jimenez. "It was actually pretty bad from what I saw."

Still, Jimenez says he didn't see what started the accident.

According to the police report, Trevino stated he entered the outside traffic lane of 1604 and was westbound for several seconds when the Jeep struck the left side of his car.

A passenger in the Jeep who survived said she and Davila were westbound when Trevino's car entered the highway from the access road and hit them in the back before they flipped over.

The police report indicates both drivers may be at fault. It says Trevino may have failed to yield the right of way while entering 1604 and Davila may have failed to use evasive action.

While no charges have been filed and while investigators report that both drivers may have contributed to the accident, one driving expert disagrees with the police report.

"The real course of action falls on the guy entering the expressway, not the person on the expressway," said GTZ Driving School instructor Alfredo Gutierrez.

Gutierrez told KSAT 12 on Monday that the driver on the expressway is not at fault. According to state law, when entering the expressway, drivers have to yield.

"As you're entering the ramp you should have made a complete stop here until it was clear and then he could have gone in," said Gutierrez. "Then he should have traveled 100 feet before he did the lane change."

KSAT 12 looked at Gabe Trevino's driving record, but only found one traffic violation. He was ticketed for speeding in his personal vehicle on February 13. The citation shows Trevino was traveling 78 miles per hour in a 65 zone.

Police on Monday did not suspect speed or alcohol contributed to the crash.

KSAT 12 talked to Trevino's wife on Monday. She didn't want to go on camera, but she told KSAT 12 she was sorry this happened and feels bad for the family of Davila, but that "this was an accident" and her husband is only being attacked because he was in uniform.