Three F-94's were in the area just northeast of the radar station, so the ground controller called one of the F-94's and told the pilot to intercept the unidentified target. The F-94 pilot started climbing out of the practice area on an intercept heading that the ground controller gave him. When the F-94 was at 20,000 feet, the ground controller told the pilot to turn to the right and he would be on the target. The pilot started to bring the F-94 around and at that instant both he and the radar operator in the back seat saw that they were turning toward a large bluish-white light, "many times larger than a star." In the next second or two the light "took on a reddish tinge, and slowly began to get smaller, as if it were moving away." Just then the ground controller called and said that he still had both the F-94 and the unidentified target on his scope and that the target had just made a tight 180-degree turn. The turn was too tight for a jet, and at the speed the target was traveling it would have to be a jet if it were an airplane. Now the target was heading back north. The F-94 pilot gave the engine full power and cut in the afterburner to give chase. The radar operator in the back seat got a good radar lock-on. Later he said, "It was just as solid a lock-on as you get from a B-36." The object was at 4 miles range and the F-94 was closing slowly. For thirty seconds they held the lock-on; then, just as the ground controller was telling the pilot that he was closing in, the light became brighter and the object pulled away to break the lock-on. Without breaking his transmission, the ground controller asked if the radar operator still had the lock-on because on the scope the distance between two blips had almost doubled in one sweep of the antenna. This indicated that the unknown target had almost doubled its speed in a matter of seconds. For ten minutes the ground radar followed the chase. At times the unidentified target would slow down and the F-94 would start to close the gap, but always, just as the F-94 was getting within radar range, the target would put on a sudden burst of speed and pull away from the pursuing jet. The speed of the UFO--for by this time all concerned had decided that was what it was--couldn't be measured too accurately because its bursts of speed were of such short duration; but on several occasions the UFO traveled about 4 miles in one ten- second sweep of the antenna, or about 1,400 miles an hour. The F-94 was getting low on fuel, and the pilot had to break off the chase a minute or two before the UFO got out of range of the ground radar. The last few plots on the UFO weren't too good but it looked as if the target slowed down to 200 to 300 miles an hour as soon as the F-94 turned around.