Three cell towers are believed to have been set on fire overnight - all in the south Auckland region.
Acting Detective Inspector Shaun Vickers of the Counties Manukau Police said police were investigating all three fires.
The first happened around 10.45pm in Papatoetoe's Ferndown Ave, Vickers said.
Similar incidents were then reported on Miller Rd in Mangere Bridge around 11pm and on Idlewild Ave in nearby Mangere around 12.30am.
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