The National Weather Service has issued a freezing rain warning for the Berkeley Township area on Sunday.
Less than a tenth of an inch of ice is expected to accumulate, making roads and sidewalks hazardous, police said.
Police departments reported that as many as 30 car crashes - and cars running off the road - have occurred in some towns since 6:30 a.m. Sunday morning, in addition to a handful of calls for people who fell on the ice.
Local roadways are currently being treated by state, county, and municipal road crews. Police said that conditions on main roads are improving, but secondary roads, driveways, and sidewalks are still extremely slick.
Residents are urged to use extreme caution when traveling in vehicle or on foot due to the black ice.