Traffic, which was reduced to one lane, was routed through the area by fire police.
All four patients were transported by ambulances to Washington County Hospital, said dispatchers with Washington County Fire and Rescue Communications.
Amber Izett, her mother, Trudy Izett, 33, Tom Wilson and William Izett, ages unknown, were all in the emergency room at presstime Sunday, still being assessed, a nursing supervisor said.
The investigation of the accident is continuing.
Deaths of couple ruled murder/suicide
FREDERICK, Md. - The July 28 deaths of Julio Falcon and Tina Falcon have been officially ruled a murder/suicide, said the Frederick City Police Department.
The investigation concluded that Julio Falcon, 44, fired the gun that killed 41-year-old Tina Falcon in the kitchen of her home in the 2600 block of Everly Drive in Worman's Mill that Sunday.
Police said Julio Falcon then turned the gun on himself.
Police investigating reported pistol whipping
Hagerstown City Police rushed to the first block of East Lee Street Sunday night for reports that a man had been pistol-whipped into unconsciousness.
But when officers arrived shortly after 7:30 p.m., they met with the victim, who was conscious and refused medical treatment.
An investigation into the incident began Sunday night.
Two remain hospitalized following Sunday crash
SHARPSBURG - Two of the six injured people involved in a two-vehicle accident on Harpers Ferry Road early Sunday were flown to metropolitan hospitals by Maryland State Police helicopters.
The male driver of a 1988 Plymouth Reliant was in serious condition at the University of Maryland Shock Trauma Center in Baltimore, hospital officials said Sunday afternoon.
A female passenger in a 2002 Saturn was in fair condition at Suburban Hospital in Bethesda, Md., a nursing supervisor said Sunday evening.
Washington County Sheriff's Deputy Brian Burke withheld their identities and the names of the other four less seriously injured people pending notification of family.
Those four - the driver and three other occupants of the Saturn - were transported by ambulances to Washington County Hospital. Their conditions were not available.
Deputies said the accident occurred at the intersection of Harpers Ferry Road and Hoffmaster Road at 3:38 a.m.
In a press release, Burke said the Saturn was traveling on the wrong side of the road when it struck the Plymouth head-on.
Traffic on Interstate 70 slowed by accident
Westbound traffic on Interstate 70 near the Dual Highway interchanges slowed to a crawl Sunday afternoon around 4:30 p.m. after a sports utility vehicle pulling a trailer ran into the rear of another vehicle, causing the trailer to overturn.
Maryland State Police said westbound lanes were reopened at 6:45 p.m. after debris was removed from the road. All occupants of the vehicles involved in the accident refused medical transport at the scene, police said.