University officials said Tuesday that the Kappa Alpha Psi fraternity is prohibited from conducting gatherings, programs or recruitment activities at the school during the investigation.
The national director of the fraternity didn't immediately return a telephone message left at the group's headquarters in Philadelphia.
Delaware State Police say a sedan travelling southbound on State Route 1 on Saturday afternoon crossed the median, spun into the northbound lanes and was hit by a pickup truck.
The driver and front passenger of the sedan were critically injured. The two rear passengers were hospitalized in stable condition after the crash.
Relatives of the driver say he's on life support.