A serial firebug in a skirt and sneakers went on an arson spree in Brooklyn and Manhattan, lighting more than 20 small blazes at churches, apartment buildings and parked cars and other spots over a fiery three-hour stretch, the feds allege.

Bryan Oviedo, 32, was caught on video setting a blaze at the Church of St. Luke and St. Matthew in Clinton Hill and trying to torch a four-story apartment building in Prospect Heights while its occupants slept during the Aug. 20 spree, federal prosecutors in Brooklyn alleged Monday.

Oviedo’s been linked by video footage to a score of other fires, all between 3 and 6 a.m. that day, prosecutors allege. Federal authorities took Oviedo into custody over the weekend, and the suspect is slated to be arraigned Monday in Brooklyn Federal Court.

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