"I've been on some bad accidents, but nothing of this magnitude," she said.
Brian Guyer, a meteorologist with the National Weather Service in Sterling, Va., said the storm was caused by cold air in the upper atmosphere that quickly followed yesterday's mild early afternoon temperatures.
"We had a lot of reports of pea-size hail covering the ground in spots," Guyer said. Among the places reporting such hail were northern Baltimore County, Carroll County and Fairfax County, Va.
The accidents had repercussions up and down the highway.
At the Maryland House Travel Plaza on I-95 in Aberdeen shortly after the accidents occurred, "people were milling around, trying to figure out how to get on to alternative routes," said general manager Vernon Bingham. The plaza was later "real quiet" when the interstate closed, but business was picking up later in the evening, he said.
Motorists taking those alternative routes clogged Philadelphia Road, U.S. 40 and Belair Road through much of the evening, officials and businesses said.
"This traffic out here is bumper-to-bumper coming and going," Marilyn Hoerr, the cashier at Steve's 40 East Restaurant on Pulaski Highway near Ebenezer Road, said early last night.
Sun staff writer Richard Irwin contributed to this article.
Southbound mile marker 69.5 (just north of White Marsh Blvd.)
Southbound mile marker 69.6
Southbound mile marker 70.8
10 vehicles, including a tractor-trailer that rolled into northbound lanes
Southbound mile marker 71
3 crashes within a quarter-mile
Southbound mile marker 71.8
Northbound mile marker 78.8 (just north of Md. Route 24 in Harford County)
1 vehicle overturned
Southbound mile marker 79.8
Southbound mile marker 80.3 (near Belcamp in Harford County)
Southbound mile marker 80.5