(CNN) Hundreds of schools and businesses in Houston remained closed Friday as crews attempt to repair a water main that provides up to half of the city's water.

A day after the 8-foot diameter water main pipe burst in east Houston, much of the city remains under a boil-water notice and restaurants without water were ordered to cease operations immediately by the city's health department.

On Thursday, firefighters in boats and high-water vehicles rescued at least three drivers when water spewing from the broken main submerged some freeways and streets in east Houston, the fire department said.

Water was slowly draining from a highway in east Houston after a water main broke on Thursday.

Water flowed nearly two miles away, Harris County Sheriff Ed Gonzalez said.

Mayor Sylvester Turner said in a statement that a contractor "was doing exploratory work" for a city water line project on Thursday when soil was moved from the line and the line burst. Blaming aging infrastructure for the incident, Turner said the water main was 35 years old.

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