Daley was taken to Jefferson Memorial Hospital and pronounced dead on arrival there, state police said.
Two occupants were able to escape
Two of the occupants were able to get out of the truck and were on the bank when rescue crews arrived, officials said.
Nicole Moreland, 26, of Harpers Ferry, W.Va., and Scott Kemp, 33, of Frederick, were taken to City Hospital in Martinsburg, W.Va., where they were treated and released, West Virginia State Police said in a news release.
The accident occurred about 4 a.m. when the truck, driven by Kevin Phelps, 30, of Harpers Ferry, went off the north edge of River Road.
The Ford F-350 struck several trees before going over an embankment and landing in a backwater area of the Potomac River on the driver's side, according to a West Virginia State Police news release and rescue crews.
Phelps fled the scene and was being sought by state police on Sunday, according to the news release.
After reaching the Potomac River outside Shepherdstown, River Road parallels the river. Past Trough Road, River Road turns away from the river in the area of Knott Island, where the truck went into the backwater area, according to Morgan and Smith.
Medical Examiner: Daley's body to be sent to Morgantown
At the scene Sunday afternoon, several damaged trees could be seen and some debris was floating in the water.
While it is believed that Daley drowned, her body was expected to be sent to Morgantown, W.Va., today to determine the exact cause of death, said Carole Spessert, a medical examiner for Jefferson and Berkeley counties.
State police could not be reached for further comment on the incident Sunday afternoon.
Morgan said he did not know why the truck went off the road.
"It was very strange," Morgan said.
It was difficult to get the truck out of the water and members of the Independent Dive Rescue Team ? who were wearing dry suits ? helped to get the truck out of the water, said Morgan and Smith.
"We were down there several hours helping them out," Morgan said.
Anyone with information about the crash can contact state police Trooper J.A. Meeks at 304-725-9779.