Police say a trooper approached the vehicle early Sunday morning when it was stopped on the shoulder of U.S. 13 in Laurel.
Police say the driver of the car had been vomiting, and that the trooper smelled alcohol on the driver's breath.
Troopers searched the car and found a handgun along with about 2 ounces of marijuana, some cash, a bulletproof vest and a mask.
Arrested were 26-year-old Breyon Baine of Seaford, 25-year-old Tyshaun Williams of Bridgeville and 23-year-old Enoch Williams of Seaford. All three face gun charges including possession of a firearm by a person prohibited.