Police believe the suspects are two men and two women between the ages of 17 to 19 years old.
The attack occurred about 4:45 a.m. on July 9 at the QuikTrip at 109 E. Northside Drive.
The 64-year-old man was at a gas pump when he was approached by an unknown man, police said. The attacker sprayed the victim with the chemical, but the victim sprayed him back with gasoline and the suspects fled the scene, police said.
But the crew returned a short time later and sprayed the 64-year-old man a second time with the chemical. This time the man ran toward the store as the suspects ran across North Main Street.
Detectives noted that before the 64-year-old man was attacked the group had followed at least one other customer to a car parked near the front of the store, but they eventually turned away.
Anyone with information should call Fort Worth police at 817-392-4469.