This is as close as police and rescue would allow bystanders. All of the vehicles to the right of the EMS vehicle are attending the scene.
There are at least 5 police cars, some are not in the image to the left side. There are fire trucks, two ambulance services, spill-clean-up specialist and perhaps others that I could not see from my vantage point.
When this shot was taken they were getting ready to move the injured truck driver from the EMS vehicle to the STARS helicopter ambulance. STARS is an abbreviation for "Shock Trauma Air Rescue Service Foundation".

Nikon D800, AF-S Nikkor 16-35mm F/4 VR, hand-held
Exposure = 1/400s f/10.0 at 16.0mm iso100, aperture priority, matrix metering