Secret Underground Tunnels / Bunkers?

I have a REALLY vague memory of attending carmichael middle school and peeping around as a kid, and finding a basement door in the school. I asked the principle and he said it was a WW2 Tunnel connecting to Richland High.
When I was in my pre-teens I found vents by the side of the high school stadium.

Does anyone else know anything about this? Its really gotten me interested and I want to see if I can find anything else out.