The crew was driving up Marks Avenue near Belmont when they made the discovery. After pulling over, they found an opening in the ground with debris on fire inside.
We were there as crews from the urban search and rescue team used a camera to look through the tunnel. Authorities say inside the tunnel was trash, drug paraphernalia and human waste nearby.
We are also told it was underneath the pavement of what used to be a company called the California Compress.
No word yet on if anyone was inside.