BNSF reported to the NRC that at 6:00 PM that 18 cars derailed. According to the local haz mat team one of the cars is leaking ethanolamine. A vapor cloud caused a half mile evacuation around the area. BNSF was contacted and reported that 4 other cars containing hazardous materials derailed. 2 contain vinyl acetate, 1 contains styrene monomer, and 1 contains tetra fluoroethane. TCEQ is conducting air monitoring. The EPA Response Duty OSC and 2 START are responding to assist with air monitoring.