Heat and humidity boiled up a powerful brew of thunderstorms that crossed Central Maryland yesterday afternoon after toppling a dairy farm building under construction in Frederick County.
A severe storm or tornado warning for much of Carroll County shut down the government for about 20 minutes as employees in the County Office Building in Westminster - including the commissioners - took shelter in the basement.
No tornado was confirmed, but the storms were severe enough to disrupt electrical power to 19,000 homes and businesses - including 9,000 in Baltimore and 4,000 in Baltimore County.
By 10:30 p.m., 5,000 customers in Baltimore remained without power, 600 in Baltimore County and 6,000 in Carroll, said Clay Perry, a spokesman for Constellation Energy Group, parent company of Baltimore Gas and Electric.
Perry said power was expected to be restored to all customers by early today.
Widespread but minor damage was reported by Baltimore County police - "trees down, lights out and many, many, many burglar alarms," said Cpl. Ronald Brooks.
Police said several large trees were uprooted along Liberty Road in Randallstown, knocking out traffic signals in the area.
No injuries were reported in Randallstown, but the collapse of a dairy cow building under construction on the farm of Jeffrey and Tammy Wivell on Dry Bridge Road southeast of Emmitsburg injured four workers.
"It just seemed like a normal storm coming through, the wind and the rain," said Tammy Wivell. "Milking was going on when the storm hit - the guys in the barn didn't know anything."
But outside, wooden trusses that the construction crew had nearly completed were blown apart, sending a shower of lumber onto four men. None of the injuries was believed to be life-threatening.
Michelle Margraf, a meteorologist with the National Weather Service in Sterling, Va., said the storms broke out of southern Pennsylvania about 3 p.m., heading from northwest to southeast.
Margraf said the storm packed heavy winds, with sustained gusts of nearly 70 mph reported in Emmitsburg. The line of storms continued across Carroll, Baltimore, Howard and Harford counties.
The biggest mess during the storm had little to do with the weather. A trash truck caught fire during the evening rush hour on Interstate 95 in Howard County.
Burning refuse had to be emptied from the truck onto the shoulder of the interstate north of Route 100 about 5:15 p.m., bringing northbound traffic to a standstill in the wind and pelting rain.
Nearly two hours later, a pile of garbage the length of three cars and up to 5 feet high remained lumped on the side of I-95 - the smell choking as passing drivers on both sides of the highway slowed to look at the mess.
State police and firefighters ordered that the truck dump its trash to make sure the flames were completely extinguished.
Sun staff writers Maria Blackburn, Julie Bykowicz, Tim Craig and Richard Irwin contributed to this article.