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Authorities have determined that tombstones disturbed at a historic Jewish cemetery in New York this weekend were damaged by environmental causes and not by vandalism.

A New York City Police Department hate-crime task force had been investigating whether the damage to the granite and marble tombstones at Washington Cemetery in Brooklyn was intentional.

The task force concluded its investigation on Sunday, finding that the cause was environmental, which can include soil erosion and lack of maintenance.

News of the disturbed tombstones came amid a series of bomb threats and vandalism targeting Jewish institutions, including cemeteries, schools and community centers.

Last week, at least a dozen headstones were toppled at a Jewish cemetery at the Waad Hakolel Cemetery in Rochester, New York, following similar incidents in St. Louis and Philadelphia. In late February, at least 170 headstones were damaged at a Jewish cemetery in St. Louis.

New York Gov. Andrew Cuomo will launch a statewide investigation of the vandalism at the Waad Hakolel Cemetery in Rochester, New York, and the overall rise in crimes targeting Jewish organizations throughout the state.

Members of the Muslim community in St. Louis have started a fundraising effort to help pay for the toppled headstones to be repaired.

Since the start of the year, four mosques have gone up in flames, according to the Council of American-Islamic Relations, which documented 139 incidents of “damage/destruction/vandalism” at mosques in 2016 — the most since record-keeping started in 2009.