Boston police are investigating after someone defaced the Boston Public Library late Tuesday night.

Library officials were reportedly cleaning the graffiti — white spray paint — on Wednesday morning, NECN reported. 

The suspect or suspects had fled by the time police arrived late Tuesday night, Channel 7 reported. No arrests have been made.

The library, located in Copley Square, is one of the city's biggest attractions. 

Bostonians voiced their outrage on Twitter Wednesday morning as crews worked to remove the graffiti.