LENS, France (AFP) ― French police were holding a mentally “unbalanced” woman after an attack on one of France’s most iconic paintings, Delacroix’s “Liberty Leading the People.”

The incident happened at the recently opened northern satellite of the Louvre museum, in Lens, northern France, when a visitor scrawled on the painting with a black marker. It was not believed to have caused any permanent damage.

Prosecutors in the town said that after having received a psychiatric report on the 28-year-old woman, they would probably have her committed on Saturday.

The attack on the painting happened on Thursday evening, just before the 6:00 p.m. closing time. A security guard apprehended the woman with the help of a visitor to the museum.

The attacker scrawled “AE911” on the painting. Architects & Engineers for 9/11 Truth (AE911Truth) is a U.S. group that supports a conspiracy theory that New York’s World Trade Center collapsed as the result of a controlled demolition after the Sept. 11 attacks of 2001.