Over the past few years I had to regretfully inform several people who had very serious injuries when they tried to run across the street but not in a crosswalk, that I simply couldn't help them beyond referring them to the good doctors.
On the other hand, the law is very protective of those pedestrians who proceed across the street through the crosswalk, giving absolute right of way to pedestrians. In cases where a pedestrian is hit while in a crosswalk, the driver will almost always be found liable for those injuries, regardless of why the driver couldn't see the pedestrian (i.e. time of the day, weather condition, etc.).