A fifth car fire in less than a week has struck the Castro/Dolores Heights neighborhood, this time at Hartford and 18th Streets. The first report of the fire came at 3 a.m. Sunday, as Bay City News reports, at 126-132 Hartford Street. Police are not saying that there's a connection to a series of four similar car fires in the neighborhood on Wednesday, but, obviously: similarities.

A neighbor tells NBC Bay Area, "It's definitely unnerving. The Castro is a relatively safe neighborhood and just to see that someone would do that..."

The fires on Wednesday all happened within two hours of each other, between 4 and 6 a.m., in the vicinity of Church Street and Liberty Hill.

Going back to mid-November, Sunday's fire actually marks the eighth such incident in the Castro in just over a month. Three cars were set on fire early in the morning on November 19th, also parked next to each other on Noe Street between 18th and 19th.

The San Francisco Fire Department is stumped by the case so far but the arson unit is on it, knocking on doors and tracking down any surveillance footage they can.

In related news, local bartender Ryan Salvo, whose car was one of those torched on Wednesday, has launched a crowdfunding campaign to replace his beloved, 12-year-old Jeep Wrangler, which he'd named Roxy. He says his insurance won't be covering the loss.

So it looks like we have another serial carsonist on our hands. Does everyone remember the East Bay carsonist of 2009?

Previously: SFFD, SFPD Stumped By Second Outbreak Of Torched Cars In Past Month