SAN FRANCISCO (CBS SF) — A neo-Nazi activist organization claimed credit online for a sign mocking San Francisco’s policy on undocumented immigrants which was hung over the Yerba Buena Island tunnel on Sunday morning.

The sign, reading “Danger Sanctuary City Ahead,” greeted westbound motorists heading into the city on the Bay Bridge.

It was apparently placed by “Identity Evropa,” which has been identified as a white supremacist organization and is designated by the Southern Poverty Law Center as a hate group.

Identity Evropa posted photos of the sign on its Twitter account.

Caltrans removed the sign mid-morning. It was not clear what agency, if any, would investigate the incident.

PUBLIC SERVICE ANNOUNCEMENT FROM IDENTITY EVROPA San Francisco is a dangerous sanctuary city where the law does not apply to illegal invaders. Enter at your own risk! pic.twitter.com/Ri8JnTmw1k — IDENTITY EVROPA (@IdentityEvropa) January 28, 2018

There was no word as to exactly when the sign went up. Officials admitted that the people who hung the sign had to trespass on a restricted area above the tunnel. A KPIX 5 reporter found wide open gate that led to the overpass where the banner was hung.