Based on my own experience; I’d say it’s not likely the driver just wandered off the left side of the road and drove all the way across the grass median into oncoming traffic. If driver distraction or inattention was the cause here, a more likely scenario is that the driver wandered off the RIGHT side of the road and over-corrected when steering back to the left.
I have read that is what they think may have happened. The truck driver and passenger, driver of car #1 (hit first) were all taken to the hospital, treated and released.
The road is a limited access, 4 lane toll road with grassy medians and no median barriers. The speed limit is 65.
Delaware said that after investigation, if warranted, they will charge the driver of the truck (who is a Maryland resident). So far, no charges warranted.
Delaware does have a seat belt law - driver's responsibility to be sure all passengers are belted in - none of the four girls were.