A complaint about a suspicious passenger resulted in a police investigation that delayed a Manhattan-bound Long Island Rail Road train for 30 minutes Thursday in Bethpage, railroad officials said.

But the suspicious passenger -- and his suspicious bag -- turned out to be a dentist and his equipment, railroad spokesman Aaron Donovan said.

The delayed train was the 7:57 a.m. train from Ronkonkoma to Penn Station, he said.

No one was injured.

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The railroad said a report was made to Metropolitan Transportation Authority police, who then requested the assistance of Nassau County police to investigate what Nassau police said was reported as a suspicious "device."

It was not immediately clear what type of equipment the dentist was carrying or why it seemed suspicious.