The founder of Xi'an Famous Foods said Thursday's three-alarm fire has "destroyed" the Long Island City branch of his restaurant and that the fire was caused by unauthorized contractors using flammable tools on the roof.

"I spent the morning with representatives from various departments on the premises," Jason Wang, the company's founder and CEO, said in an email Friday. "While we are still pending the official report from the fire marshal, based on in person conversations I've had with them today on site, they have reviewed security tapes from nearby buildings and are confident that the fire was caused by contractors working on our roof with flammable tools (such as a torch). These contractors were not employed by our company, and gained access to our roof from behind our building. We were not notified and had no knowledge of their presence until the smoke began to pour into our store by the way of our AC. At this time, we do not have the report to be able to comment on who sent the contractors and what work they were doing exactly."

A spokesperson for the FDNY said they could not comment on Wang's statement, and that the fire marshal investigation was ongoing.

One civilian sustained non-life-threatening injuries, the FDNY said Thursday.

Wang said the fire destroyed the entire building.

"The extent of the damage is great, as described in previous reports. The entire building is destroyed and the building is contaminated to the extent that all affected food, supplies, and equipment will be disposed of in accordance with applicable laws, regulations, and best practices," Wang continued in his email.

It's unclear if Wang will reopen the restaurant in that location, he said later: "We are uncertain about this location at this time, as the damage is extensive. Regardless we are exploring all options to be back up ASAP."

He added that he wanted to clarify the fire did not start in the restaurant's kitchen.

"I hope my update will help clarify the situation so the public understands what actually transpired and that while it is most likely the first stereotypical reaction to blame the fire of a Chinese restaurant on a grease fire, it is far from the truth. We take great care in making sure our restaurants are safe and enjoyable places for our guests and staff alike. We have been doing so for 15 years in business, and we will continue to do so for the days to come," he said.