It took Nassau County police and fire officials about an hour Wednesday morning to determine that a suspicious package at the Oceanside post office was just leaking a nonhazardous liquid.

“Deemed nontoxic,” said a police spokeswoman after a stretch of Atlantic Avenue was closed as police and fire personnel investigated the report of a suspicious package at the post office.

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Police said an employee at the post office at 80 Atlantic Ave. found a box leaking a liquid and it was reported to police just before 6 a.m.

Police and fire personnel investigated, and Atlantic Avenue was closed between Court Street and Lincoln Avenue, the spokeswoman said.

The box came from the Garden City post office, and the delivery truck that carried the box was searched, too, the police spokeswoman said.