CHICAGO (CBS) — A series of suspicious car fires are under investigation in Wrigleyville and Boystown. In all seven vehicles were burned, four of which are destroyed.

Police say it all started just after 2 a.m. Tuesday when they were called to the 3500 block of North Clark. When officers arrived they found a mattress on fire.

Two hours later, police were called back and that’s when the burned out cars were found.

The Chicago Bomb and Arson Unit is now investigating the fires.

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