The workers became trapped around 11:10 a.m., while relocating utility lines at an energy plant near the airport for its redevelopment project, a spokesperson for the Port Authority of New York and New Jersey said.
A stop order for all construction at JFK has been issued. The Port Authority is conducting the investigation.
Photos from Fox5 show equipment surrounding what appears to be a trench.
Flight operations at the airport were not affected.
The victims' identities were being withheld pending notification.
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