PORTLAND, Ore. (KOIN) — Delays continue on the Steel Bridge Thursday after a fire ignited under the bridge inside a tunnel where officials discovered a homeless encampment.

When crews arrived at the Steel Bridge Wednesday afternoon, Portland Fire & Rescue said smoke was seeping through the cracks of a “decorative cinderblock wall” underneath the west end of the bridge. Using sledgehammer-like tools, firefighters knocked out a large hole in the non-load-bearing wall.

Inside, a large blaze was burning materials officials said were brought in by the people living in the tunnels. Battling the blaze wasn’t easy, according to PF&R spokesperson Rick Graves, who said firefighters had to enter the area through a manhole.

Once the fire was put out, PF&R said crews began an extensive search of the area, which was covered in needles and trash, and discovered that the people living there had dug multiple tunnels and created flat areas by moving soil.

“Extensive tunnels and areas you wouldn’t naturally think someone could be, but we’re now doing a very thorough search to hopefully make sure that the entire area underneath the steel bridges enclosed by the cinder block area is clear,” Graves told KOIN 6.

According to Graves, PF&R rescued six people from the fire and at least one person was taken to a hospital with serious burns and smoke inhalation.

PF&R told KOIN 6 that it doesn’t appear the tunnels have impacted the bridge’s stability, but Oregon Department of Transportation engineers will be evaluating the bridge to make a final determination.

The fire bureau said that the official cause of the fire is still under investigation.

There is no estimated reopening time for the Everett Street ramp to the eastbound bridge.

Stay with KOIN 6 for continuing coverage.