A St. Leonard Volunteer firefighter suffered serious burns late Thursday while battling a two-alarm fire inside a Prince Frederick store, authorities said.

Volunteer fire crews were called to a flooring store in the 100 block of Security Boulevard at about 11 p.m., fire officials said. The firefighters saw heavy smoke coming from the roof and started an interior attack, said Senior Firefighter Michelle Sigona, a spokeswoman.

But soon afterward, officials declared the building unsafe and ordered firefighters to leave the building. Two firefighters were initially missing, and officials sent out a Mayday, Sigona said.

One of the firefighters was quickly located, and a second managed to escape a short time later. The second firefighter received burns and was taken to a hospital with non-life-threatening injuries, Sigona said.

The cause of the fire is under investigation.