According to the Westfield Fire Department, 5 rail cars derailed in the area of East Mountain Road on the lines operated by CSX.
The cars were carrying 100,000 tons of trap rock.
The cars are still standing up right and nothing dumped out.
There are no injuries.
Fire officials emphasize there is no public safety threat.
The tracks are used for both freight and passenger trains.
At this hour, one track remains open so delays should be minimal.