A fire at an indoor shooting range in Horsham, Pennsylvania, forced firefighters into a difficult and dangerous fight, complicated by ammunition inside the building.

Crews were called to Easton Road in Horsham just after 2:30 p.m. Monday, and the road remained closed for hours as crews worked to get the scene under control.

At the scene of the fire, employees of Clayton's Range & Shop stood in the cold, watching firefighters work to save what they could from a business many said has been a staple in the area for decades. The small business is now in ruins.

"It was a small, family business," said Dave Swindell, who works nearby.

The fire was even more dangerous because the building was filled with with ammunition. At one point, the Philadelphia Police Department's bomb squad went to the blaze to assist firefighters.

As smoke poured from the building, crews discovered the very design meant to keep people safe on the range also made the fire harder to fight.

"It's constructed with steel and thick rubber, so the fire was deep-seated and very tough to access," Lee Greenberg, the fire chief of Horsham, said. 

To reach the flames, crews brought in a backhoe and knocked down part of the building in what officials called a controlled collapse. Then came some relief.

"The bulk of the fire was contained to the range area, not the showroom where the ammunition and the guns were," Greenberg said. 

Firefighters said the range area was largely destroyed, and the showroom and other areas had heat, smoke and water damage.

Off-camera, employees told CBS News Philadelphia they're in shock and will have to find new work, but grateful no one was hurt.

Neighbors said the road ahead won't be easy.

"It sucks, you know? It's going to be a lot to rebuild," Swindell said. 

While Greenberg said the fire may have had something to do with the HVAC system, the cause is still under investigation.