Police said in a news release that seven people involved in the second wreck on U.S. 340 at Keep Tryst Road were taken to area hospitals, including Washington County Hospital and Frederick Memorial Hospital.
Police said that in the first accident, the 17-year-old driver of a 1993 Geo Metro lost control of the car and hit a guardrail "for reasons unknown at this time."
Trooper Jim Ardinger said two passengers were thrown from the back seat of the Metro, including one who was thrown over a guardrail and down a bank.
Police said in a news release that "the names of the two 18-year-old rear seat passengers are being withheld pending notification of their families. The name of the driver cannot be released until the seriousness of the passengers' injuries are known."
The second accident was near a bend in the road where oncoming cars might not have been able to see cars stopped ahead because of the first accident, said Scott Osborne, a paramedic with Boonsboro Ambulance and Rescue Inc.
Ron Lowe, of the Brunswick Engine and Truck Co., said he was setting up warnings for motorists approaching the first accident when the second wreck occurred.
Six vehicles, including a 2002 Hyundai, a 1986 Chevrolet pickup truck, a 2002 Ford Expedition, a 2003 Dodge Ram and a 1995 Dodge pickup carrying a 24-foot enclosed trailer loaded with construction equipment were involved in that pileup.
According to a news release, the driver of the 1995 Dodge pickup carrying the trailer, John Robert Crum, of Branchville, S.C., was charged with negligent driving in connection with the pileup.
Crum was traveling eastbound, was unable to stop and struck a 2002 Hyundai, driven by Montaz Flood, of Baltimore. All passengers of the Hyundai were transported to hospitals for non-life-threatening injuries, according to the news release.
Maryland State Police Trooper Andrew Smith of the Hagerstown barrack said that the pickup crashed into several more cars that were stopped, some for several minutes, because of the previous accident.
"He was bouncing around from the fast lane to the slow lane, smashing into cars," Smith said.
As part of the pileup, a 2002 Ford Expedition, driven by Nancy Clef Lewis, of Fort Walton Beach, Fla., was pushed into a 2003 Dodge Ram driven by her husband, John M. Lewis, police said in a written release.
Smith said all of the injuries in the six-vehicle pileup were considered minor. He said the most serious were to a six-month pregnant woman.
Seven occupants of the vehicles involved refused medical treatment at the scene, including Crum, police said in a written release.
Traffic was backed up on eastbound U.S. 340 for several miles following the accidents. Several motorists said they either saw or just missed being involved in the pileup.
Steve Grams, of Frederick, pointing to the pickup truck with the attached trailer, said, "I heard this truck skidding behind me. When I got out of the car, people were trying to get out of their cars and some guy was stumbling around and collapsed."
Lisa McConkey, of Middletown, Md., said, "We're really shaken up. I don't know how we didn't get hit by the pickup with the trailer. It's the scariest thing I ever ... I thought we were going to die."
Dozens of firefighters were on the scene helping clean up glass and metal thrown from the vehicles in the pileup.
Several ambulances and tow trucks could be seen driving along U.S. 340 and on Md. 67.
Bobby Webster, the assistant store manager at a Sheetz convenience store in nearby Knoxville, Md., said he heard that the accident was causing two- to three-hour delays.
Webster said a store employee called from the accident and "She said it was going to be about two hours ... Another customer said it was to be about three hours."
Police said in a written release that the road was reopened at about 11:30 p.m.
Staff writers Gregory T. Simmons, Dave McMillion and Pepper Ballard contributed to this story.