Waymo car was the only thing at fault. Drivers are expected to stop to the side when they see the lights. I guess the red SUV could've slid behind the Waymo to let the ambulance do the same, but it'd be unwise without the police telling you to do so, could hit a cop on foot. Silver car could go forward, but you don't squeeze in front of a U-turning car, and doing so could've made things worse for all they knew.