Police were investigating why a set of baseball bats were chained to telephone poles around San Francisco on Thursday, police said.

As many of 15 of the bats, some of which had nails protruding from them, were found in a number of locations around the city, Sgt. Michael Andraychak said.

The bats were discovered throughout Thursday, beginning in the morning. The last one was found at around 4:45 p.m. at 19th Avenue and Buckingham Way, Andraychak said.

Andraychak said there were no indications of who placed the bats or why. Police were investigating various aspects of what Andraychak described as a “very strange” episode.

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