Heavy rains yesterday afternoon caused a series of accidents on Virginia roadways that injured more than 30 people, at least one seriously, and clogged rush-hour traffic, police said.

Shortly after 3 p.m., 22 vehicles were involved in several small crashes along a three-mile stretch of westbound Interstate 66 near Centreville, according to Virginia State Police spokeswoman Lucy Caldwell. About 20 people were taken to area hospitals to be treated for minor injuries, she said.

"There were quick, heavy downpours blanketing the area at the time," Caldwell said. She said the rain hampered visibility and caused the roads to become "very slick."

At 3:30 p.m., at least 15 vehicles, including a tractor-trailer, were involved in a pileup on northbound Interstate 95 about a mile north of the Lorton exit, Caldwell said.

"There were several wrecks sliding into each other, a domino effect," Caldwell said.

Caldwell said one person suffered serious injuries and was flown by helicopter to a hospital; 14 others were taken by ambulance.

Traffic on both highways was backed up while police cleared the wreckage.

Police said westbound I-66 was reopened by 4:30 p.m. and two lanes of northbound I-95 were opened shortly after 5 p.m.

CAPTION: Emergency vehicles leave the scene of a multi-car accident on northbound Interstate 95 at the Lorton exit.