A Merrick man was pronounced dead Tuesday afternoon in Manhattan after trading blows with a bike messenger in front of a tony Park Avenue tower, authorities said.

Officers found an unconscious Roger Balan, 58, shortly after 12:10 p.m. outside midtown's 440 Park Ave., where he worked as a porter, the NYPD said.

Balan, of Briarcliff Drive, had been arguing with a 35-year-old bike messenger and may have had a medical episode, an NYPD spokesman said.

No obvious sign of trauma was found on Balan, who was pronounced dead at Bellevue Hospital Center, police said.

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The medical examiner's office will determine cause of death, police said.

The bike messenger was taken into custody for questioning, but has not been arrested, police said.

---- ELLEN YANCorrection: A previous version of this story gave the wrong time for the 911 call.