PHILADELPHIA (AP) — The Philadelphia Fire Department said “several” firefighters and a city inspector became trapped when a building collapsed during a fire response early Saturday, with more than one person still under the rubble hours later.

“So far, several were rescued and transported to hospitals. Work continues to free others,” the fire department tweeted. It said an “L&I inspector” was among those caught in the collapse, apparently referring to the Department of Licenses and Inspections.

It was not immediately clear how many people were still trapped, their condition or the condition of the injured. The department did not answer a phone call seeking comment.

The tweet included a photo of the scene, which showed a pile of rubble and bricks surrounded by dozens of firefighters and other emergency responders.

No signs of smoke or fire were visible in the photo, however, the tweet said, “The fire response remains at 2-alarms.”

About four hours earlier, just after 2:05 a.m., an official fire department Twitter account for automated alerts sent a tweet warning people to avoid a fire at an address in the Fairhill neighborhood of northern Philadelphia.

That was immediately followed by a brief tweet listing the same location and the words, “UPDATE: All Hands.” At about 2:20 a.m., another tweet said the fire was under control, listing the same address.