Updated 5/14/11 2:03p.m.

SCHAUMBURG, Ill. (STMW) – Authorities are investigating after a fire started overnight at a mobile office unit and spread to a building nearby at a concrete business in northwest suburban Schaumburg.

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The fire started about 3 a.m. on the north side of the 900 block of West Irving Park Road, but did not occur at the airport located across the street, said Schaumburg police Sgt. John Nebl.

The fire started inside a mobile office unit of a concrete contractor business, and it spread to a building next door — their headquarters, Nebl said. No one was hurt, but it was not known what started it.

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Nebl said the fire did not affect the airport and the cause of the fire is under investigation.

A fire department representative could not be reached late Saturday morning.

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