WASHINGTON — Flooding has closed schools and blocked roads after heavy rains in parts of Maryland, Virginia and Delaware.

Flood warnings and advisories are in effect Friday along much of the Atlantic coast. Some school systems closed on Maryland’s Eastern Shore and some schools in Delaware and Virginia’s Eastern Shore opened late.

The National Weather Service says the region’s hardest hit area is southern Delaware, where 8 to 12 inches has fallen since Wednesday. Parts of southwest Virginia could get 2 to 3 inches of rain into Friday night.

Virginia State Police say 35 vehicles, including 16 tractor trailers, were involved in 15 crashes along a two-mile stretch of Interstate 81 near Christianburg as heavy rain moved through Thursday. Police say multiple people were injured and the highway was closed for hours.