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.

S.F. Danger

(Identity Evropa via Twitter)

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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.

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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.

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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.