The theft happened Aug. 12 at R&E Collision Center, where the car had been undergoing repairs for about a year following a crash.
"We've been here for about 20 years, 25 years. We've never had a case like this," shop owner Giovanni Robles said.
Surveillance video captured the group breaking a lock, opening the shop's gate and rolling the Impala out of the lot and onto the street. The thieves then used a two-wheel dolly to take the car.
"They came in a '01-'05 Chevrolet Avalanche," Robles said.
The Impala had received a fresh coat of paint three days before it was stolen. It was parked outside, behind a locked gate, as the paint cured.
Robles said he believes the thieves may have watched the business before carrying out the theft.
"I believe they were patrolling the area for quite some time. I'm sure we were under surveillance," he said.
The classic car is valuable and also holds sentimental value for its owner, according to Robles.
"Estimated around $60,000 to $80,000 worth of a classic car," he said.
The Impala has been missing for about 10 days, raising concerns that its appearance may have been modified.
"We're very scared right now. We don't know if we might get hit again," Robles said.
Robles is increasing security at the shop, which houses other high-end classic vehicles.
"We're putting up a lot of surveillance now. More cameras. We're actually looking to hire a security guard," he said.
Anyone who may have seen the Impala or has information about the theft is asked to contact the Los Angeles County Sheriff's Department.