Firefighters were battling a fire at Jim’s Steaks in South Philadelphia that broke out Friday morning and continued to burn into the afternoon, going through the restaurant’s HVAC system. More than 100 firefighters responded to the blaze but were having trouble extinguishing it because the flames appeared to be difficult to reach as they traveled through the building’s heating, ventilation and air conditioning system, Philadelphia Fire Commissioner Adam Thiel said at a news conference shortly before at 2 in the afternoon “We are very concerned about the structural stability of this building. There’s really almost no way to evaluate this,” Thiel said. “So again, we’re taking a very cautious defensive stance and hopefully we’ll be able to preserve as much of the property as possible — at least the building itself.” Firefighters responded to the restaurant at the corner of 4th and South streets after someone reported some wires on fire around 9:15 a.m., Thiel said. Smoke could be seen billowing from every floor of the four-story building as firefighters smashed windows. The floors atop the cheese shop, a city staple dating back to the 1930s, were vacant and being used for storage, Thiel noted. A manager at the restaurant told NBC10 the air conditioning stopped working in the morning and then it started smoking. That’s when he said he got everyone out of the building. Everyone was fine, the manager said. NBC10’s Miguel Martinez-Valle was at the scene and reported just after 11 a.m. that firefighters were being evacuated from the building and bystanders were being called for backup. Firefighters appeared to be focusing their efforts on an HVAC unit, dousing it with water from above and below. However, Thiel said, crews did not “smother” the building with water because they believed the fire was in the ducts. The fire was contained to the restaurant, but crews were proceeding with caution due to the risk that the building was structurally unstable. “This is a very challenging incident, and right now we’re trying to balance the risk and benefit to the lives of our firefighters and protect the property here in this iconic building and everywhere connected to it,” Thiel said, referring to an incident in which a firefighter died last month after a building collapsed following another fire.