flashing, tall, white strobe lights over an Illinois cornfield

We were driving home going South on Randall Road from the Spring Hill Mall at around 10:00 p.m. All of a sudden we saw a series of tall bright white, flashing lights over the cornfield. The lights themselves were tall bars that flashed quickly parallel to the ground down a line like a strobe light. They looked close, like 40 feet from the ground. We saw a huge dark shape in front of the lights. The object flahed the lights and looked like it was moving south down Randall road, but then disappeared quickly.
Witness indicates that the date of the incident is approximate.  PD