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The Gainesville Sun, Matt Stamey, Associated Press
Officials work at the scene of a multi-vehicle wreck on Interstate 75 at Paynes Prairie on Sunday, Jan. 29, 2012, south of Gainesville, Fla.

GAINESVILLE, Fla. — Authorities are still trying to determine what caused a horrific pileup on Interstate 75 in north-central Florida that left at least 10 people dead and injured at least 18 others.

The pileups of cars and trucks happened around 3:45 a.m. Sunday on both sides of I-75 south of Gainesville.

Police say the dark Florida highway was so shrouded in haze and smoke that drivers were blinded.

Authorities say the interstate had been closed for a time before the accidents because of a mixture of fog and heavy smoke from a brush fire that may have been intentionally set. It was reopened when visibility was deemed to have improved.

The highway was shut down most of Sunday as investigators pored through the wreckage and police notified the relatives of victims.