CHICAGO (AP) – Emergency crews are battling massive fires at a northern Illinois chemical plant that exploded into flames. The Monday morning explosion that sent huge plumes of thick black smoke into the air prompted officials to order an evacuation of residents and business to the south of Chemtool Inc., near Rockton. Trisha Diduch, the planning and development administrator for Rockton, says she estimates about 1,000 people are affected by the evacuation order. There have been no reports of injuries, and the company says everyone on site is “safe and accounted for.” The plant manufactures grease products, lubricants and other fluids. Rockton is located near the Wisconsin border, about 95 miles northwest of Chicago.