FLATBUSH, Brooklyn (PIX11) — A man hopped onto the subway tracks in Brooklyn, picked up a rock, got back onto the platform and used the rock to bash a 64-year-old victim in the head repeatedly on Saturday, police said. 

The victim was in the Avenue H train station shortly after midnight when the attacker walked up, officials said. The two argued before the physical attack. 

The 64-year-old man was knocked out, police said. He was taken to a hospital with trauma to the head. 

The attacker fled the station. Police have asked for help identifying him. The man is believed to be in his 30s. He’s about 5 feet, 9 inches tall and weighs around 170 pounds. He has brown eyes and black hair.

Submit tips to police by calling Crime Stoppers at 1-800-577-TIPS (8477), visiting crimestoppers.nypdonline.org, downloading the NYPD Crime Stoppers mobile app, or texting 274637 (CRIMES) then entering TIP577. Spanish-speaking callers are asked to dial 1-888-57-PISTA (74782).