The attack happened Sunday morning near Walton Avenue and East 149th Street in Melrose.
Investigators said two males were on the roof of a nearby building when one of them threw a rock at the victim, hitting him in the head.
The other male threw a wooden two-by-four, also hitting the man in the head, police said, before both suspects took off.
A mechanic working in his shop across the street heard the man yell, and ran over to help him.
"I go over there, I cleaned his face," said neighbor Gabriel Ayala. "I call the ambulance, I call the cops."
Ayala added the victim had no idea what happened to him because he said something had come from the air.
Several neighbors told Eyewitness News they've complained and police need to do something about a loud, disruptive group of young people who've been trespassing in their yards and on their roofs.
"They need to put a stop to them," added neighbor Pedro Lopez. "You can talk to anybody. He's just a very lovely person, he is very well known in the community. He's like a father to everybody around here."
Medics rushed the victim to New York City Health and Hospitals/Lincoln, where doctors used 15 staples to close the wound to the man's head.
Both suspects were caught by surveillance cameras in the area.
Police are asking anyone with information about the case or either suspect to contact them.
Call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782). You can also submit tips by visiting the CrimeStoppers website at crimestoppers.nypdonline.org or by messaging on Twitter @NYPDTips.
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