A furniture warehouse in Harford County has closed its doors after more than 50 years of operation after a fire Sunday night caused significant damage to the building.

Investigators said the fire at Jarrettsville Furniture could be related to spontaneous combustion and lithium-ion batteries as possible working theories on the cause of the fire.

“It’s a mainstay of Harford County and we’re going to do everything in our power to determine exactly what caused this fire,” Master Deputy State Fire Marshal Oliver Alkire told WBAL-TV 11 News.

Officials said the fire broke out around 7:15 p.m. Sunday.

When fire crews arrived at the scene, they found heavy flames in the warehouse at the back of the complex. Investigators with the State Fire Marshal’s Office said they have determined the origin of the fire.

“We went through the debris and what we found was there’s a variety of scenarios that we’re looking at,” Alkire said.

An employee who was inside the warehouse on Sunday night is being praised for her actions when the fire broke out.

“She saw the fire and she did what we always ask; she got out, stayed out, called 911 and in the course of her exiting, she actually closed the fire door,” Alkire said. “That certainly prevented that fire from spreading through the remainder of the furniture store.”