TEWKSBURY, MASS. >> Police officers in one Massachusetts town are being told to be extra vigilant after the words "Kill Cops" were found spray painted at a skate park.

Tewksbury Deputy Chief John Voto says the graffiti was reported to police Aug. 3, but it remains unclear exactly when the message was painted. The words were accompanied by an upside-down peace symbol and a "heartagram," a hybrid heart-pentagram symbol.

Voto said the message is concerning in light of the killings of police officers across the country this year.

He says the investigation is mainly focused on the vandalism, and it is unlikely the person responsible would face charges related to the message itself unless they actually intended to kill police.