Authorities are urging drivers to find an alternate commuting route Wednesday morning as the westbound Long Island Expressway is shut down in Jericho for what police said is the investigation of a fatal auto accident.

The expressway is expected to remain closed throughout the morning rush hour. At 6:30 a.m. traffic was already backed up for miles east of Exit 41, Routes 106 and 107.

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Nassau County police said details are still emerging about the crash and could not immediately say how many vehicles — or, what type of vehicles — were involved or provide any information about victims.

The crash occurred shortly after 3 a.m., police said.

Non-commercial traffic is being urged to use the Northern State Parkway, while commercial drivers are being urged to use Jericho Turnpike or other alternate routes.

The investigation is expected to last until at least 8 a.m., if not later, police said.