Freezing rain caused at least six vehicle accidents around Butler County early Saturday morning.

A tractor-trailer jackknifed along Route 422 near Interstate 79 in Muddy Creek Township, according to 911 reports.

Multiple vehicle crashes also were reported on Downieville Road in Adams Township, Mercer Road in Center Township, Greenwood Drive in Butler Township and East Jefferson Street in Butler, according to 911 reports.

Multiple municipal road crews have been notified of icy conditions.

The National Weather Service issued a freezing rain advisory in Butler until 2 p.m. Saturday. The release said the most intense ice will be late this morning.

State police in Kittanning issued a news release advising motorists to only travel if necessary and to use extreme caution when driving on Route 28 and Route 422 in Armstrong and Allegheny counties.