WORCESTER, Mass. (WHDH) -- Three people were injured after an explosion at a dentist office at 9 Linden Street in Worcester.

Worcester fire officials said the dentist, Stanley Levenson, was taken to UMass Medical Center with second-degree burns to his face and hands.

“It’s very lucky in any incident like this, everybody came out standing up,” said Tom Gingras of the Worcester Fire Department.

Investigators said a dental assistant was putting alcohol into a lamp used to soften a denture mold when there was some sort of a flashback.

“They were filling a butane heating appliance and it was either too hot, the flame hadn’t all the way gone out, and then used alcohol in the air and the alcohol they were fueling flashed,” said Gingras.

The dental assistant suffered less serious injuries than Levenson. Fire officials described her injuries like sunburn. The patient was shaken up and escaped injury.

The flash fire remains under investigation.

The dentist suffered the most serious burns to the side of his face but is expected to be okay.