BOSTON >> Massachusetts commuters are heading to work through a sloppy mix of snow, slush and freezing rain but no major problems have been reported.

State police on Tuesday morning reported several accidents, including two jack-knifed tractor-trailers on Interstate 495 in Chelmsford and several minor accidents on Route 24 in the Brockton/West Bridgewater area.

Traffic was slow on major highways, but volume was light because it is school Christmas vacation week.

The chief of the MBTA says the mass transit system is running as normal after one early-morning switch problem was resolved.

There are no major power outages.

The National Weather Service says areas west and north of the city could get up to four inches of snow.

Gov. Charlie Baker called it a "tier 1" storm, the lowest on a 5-tier scale.