about the Phoenix crash

https://www.statter911.com/2019/04/07/video-3-dead-including-baby-in-pickup-truck-that-collided-with-phoenix-fire-engine/

have not seen any causes listed yet

let me guess

1. sun in eyes

2. suicide

3. badly misjudged speed of approach

4. saw earlier fire truck turn left - thought 2nd truck would do the same

5. driver had heart attack or seizure

6. mechanical failure in pickup

7. foot slipped from brake to accelerator

8. distracted by commotion in pickup truck - maybe the baby started to cry loudly

9. maybe the fire truck lights and siren suddenly went off and pickup driver thought that they had cancelled their Code 3 driving and would be slowing down

witnesses said they heard siren and then loud boom - no mention of any noise from pickup truck or any change in siren noise before crash - so apparently it all happened very very fast