The report of a “hazardous” white substance forced the closure of a main terminal concourse at LaGuardia Airport early Wednesday, sending three people, two of them TSA agents, to the hospital for observation, the Port Authority said.

But an investigation determined the material to be “a food item/spice” — and the terminal was reopened about an hour later, the PA said.

The incident was reported at 5:30 a.m. at a screening point Terminal B’s Concourse D, the Port Authority said.

It was there, Port Authority spokesman Joseph Pentangelo said, that the two Transportation Security Administration agents “came into contact” with the unknown white substance that was in a bag.

After an evaluation by emergency medical service personnel, the agents and a third person were taken by the FDNY to nearby Elmhurst Hospital Center in Queens.

The concourse was closed “out of caution” at 5:43 a.m., according to Port Authority spokeswoman Lenis Rodrigues. The concourse was reopened at 6:27 a.m.

Authorities did not disclose the final determination of what the “food substance” might have been. Officials were advising travelers to expect check-in delays Wednesday.

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With William Murphy