Several residents of a Hempstead apartment complex were taken to the hospital Monday morning after high levels of carbon monoxide were discovered in the building, a fire official said.

Hempstead police said the building on Jackson Street has been cleared — and residents had returned to their apartments. The Hempstead Fire Department said the incident appears to have been the result of “a faulty boiler.”

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Hempstead police said Monday night seven residents and two Hempstead police officers were taken to Nassau University Medical Center in East Meadow. The two police officers were not admitted, authorities said. Hospital spokeswoman Shelley Lotenberg said one person had been admitted and was undergoing treatment in the hyperbaric chamber. The condition of that patient was not immediately known.

The incident was reported sometime after 5 a.m.

The fire department said tests indicated “high readings” of carbon monoxide, but said the incident was later cleared.

— With Darran Simon