At around 1830 York Village Fire was dispatched to a tractor trailer accident on the highway. While the companies were en route it was reported that the T.T. unit was leaking diesel fuel and on fire. Upon arrival we found 1 Tractor trailer unit southbound just north of the York Toll plaza. The unit had jack knifed and punctured one of the diesel saddle tanks. There was approximately 175-200 gallons of diesel fuel actively leaking into the grass and nearby wetlands. A call was put out to National Wrecker service for their spill response trailer and heavy equipment. The cargo was determined to be magazines, and thus non hazardous. The unit was not on fire. It was a lengthy incident.