Officials are closing roads near Hofstra University on Monday for the first presidential debate, while operators of Nassau County’s bus service are warning of “extreme” service delays.

Hours before Hillary Clinton and Donald Trump are expected to square off at the David S. Mack Sports and Exhibition Complex, roads nearby the campus will be closed off, or partially restricted, to traffic.

“The Nassau County Police Department is advising that citizens avail themselves of alternate routes and should avoid travel in the area of the Nassau Coliseum and Hofstra University on the day of the debate,” the department said in a statement.

County officials said roads bordering Hofstra will be closed to traffic. Charles Lindbergh Boulevard and Earle Ovington Boulevard will be closed from 5 a.m. until midnight.

Officials from Nassau Inter-County Express said service to Nassau Community College, Nassau County’s Department of Social Services, Hofstra University and East Meadow will be disrupted.

Officials are urging riders to check Nice.com, Twitter, and Facebook for updates about service.

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From noon through midnight, Hempstead Turnpike will be closed from Oak Street to Merrick Avenue near Eisenhower Park. Oak Street also will be closed from Hempstead Turnpike, northbound to Westbury Boulevard.

California Avenue and Meadowbrook Place will be closed northbound at Belmont Place. Uniondale Avenue and Manor Parkway will be closed, heading north, at McKenna Place.

Nassau County officials are urging drivers to use other eastbound or westbound routes: Front Street, Old Country Road, or Stewart Avenue.

Lawrence Street in Uniondale will become a one-way street, heading north from Hempstead Turnpike to Westbury Boulevard; Courtenay Road in Hempstead can be accessed one-way, heading south from Hempstead Turnpike to Front Street.

Manor Parkway, Marvin Avenue, Walton Avenue, Gilroy Avenue, and Cunningham Avenue also will become one-way streets, for one block south of Hempstead Turnpike.

There will be no parking on Oak and Lawrence streets, Courtenay Road and McKenna Place, university officials said.

Six electronic portable message signs will project traffic delays and updates, said Eileen Peters, a spokeswoman for the state Department of Transportation on Long Island.