Ambulances are short, and not hardened. They have to prepare to treat up to 50 people immediately. The big trucks are likely rolling hospitals.
I didn’t see anything that looked like ambulances in the brief view we had when they rolled up. Whatever they are, all the vehicles did look hardened. I got the feeling the cameraman was quickly told to swing the camera away from them.
One of the trucks was carrying what looked like big tanks of water, and another had a forklift with maybe a bomb box on the front.