NewsCopter 7 was over Columbia Turnpike in Florham Park.
A geyser of water shot from the broken main across all four lanes of the highway.
Columbia Turnpike was shut down in both directions between Airport Road and Cali Drive as crews responded to the scene.
Motorists were advised to avoid the area and seek alternate routes.
There was no immediate word on the impact to water customers in the area.
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