Seven semi trucks and 12 passenger vehicles were involved in the crashes, CNN reported.
"As it was happening on the northbound side, it was happening on the southbound side as well," said Steven Camps, who was a passenger in one of the cars involved. "There was nowhere to go. It was just cars hitting cars and cars."
The crashes occurred between 11:30 p.m. Saturday and 4 a.m. Sunday, said Sgt. Todd Kelly, of the Alachua County Sheriff's Office.
The number of individual accidents remains undetermined, but they all happened on a stretch of the highway that had greatly reduced visibility because of a brush fire on Paynes Prairie, the Gainesville (Fla.) Sun reported.
The highway was closed at some point Saturday so the FHP could monitor the brush fire, but was reopened later after conditions improved. The first accident on Interstate 75 was reported shortly after the highway reopened, around 11:30 p.m. Saturday.
Interstate 75, along with U.S. highway 441, was totally shut down Sunday morning just south of Gainesville because of the poor visibility and the crashes.
"Both roadways have been shut down due to accident investigations and zero visibility. Smoke from a recent brush fire is very heavy in both areas. Motorist are encouraged to use alternate routes such as Hwy 27 and Hwy 301," said Kelly.