LONDON (AP) — Vandals have defaced a memorial commemorating victims of the London transit bombings on the ninth anniversary of the rush-hour attacks that killed 52 commuters and injured hundreds.

The park’s manager discovered the graffiti, including one slogan reading “Blair Lied Thousands Died,” at the memorial in London’s Hyde Park early Monday. Workers scrubbed off the red and black lettering just hours before a ceremony marking the anniversary was set to take place.

Four suicide bombers also died in the synchronized bombings on London’s transit system on July 7, 2005.

The monument is comprised of 52 stainless steel pillars, one for each of the victims, and cost nearly 1 million pounds ($1.7 million) when it was unveiled in 2009.

Police have launched an investigation.

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