A vandal tagged one of Mark Rothko’s works from the Seagram’s commission hanging in the Tate Modern today, according to The Independent. This photo was taken by an eyewitness and posted on Twitter:

One eye witness Tweeted: “This guy calmly walked up, took out a marker pen and tagged it. Surreal.”

The work, Black on Maroon 1958, would have a value in the tens of millions, although it was gifted to the museum by the artist.

In a short statement a spokeswoman for the Tate said: “Tate can confirm that at 15.25 this afternoon there was an incident at Tate Modern in which a visitor defaced one of Rothko’s Seagram murals by applying a small area of black paint with a brush to the painting.

The police are currently investigating the incident.“

Mark Rothko Painting ‘Defaced’ at Tate Modern (The Independent)