NEW YORK -- The madman allegedly responsible for four murders in Brooklyn was busted Saturday after slashing someone on the subway in midtown Manhattan, police sources said.

Maksim Gelman, 23, was nabbed on the subway at Seventh Avenue near Times Square around 9:15 a.m.

The condition of the person he attacked on the subway was unclear, according to police sources.

Gelman is accused of a savage murder spree that began at 5:00 a.m. Friday, when he fatally stabbed his stepfather, 54-year-old Aleksandr Kuznetsov, in Sheepshead Bay.

Eleven hours later, Gelman stabbed his girlfriend Yelena Bluchenko, 20, and her mother, Anna Bluchenko, 56, just as Yelena Bluchenko called 911 for help.

As cops rushed to the scene, Gelman escaped in a car he had stolen earlier in the day.

At the corner of 24th Street and Avenue U, he carjacked another vehicle, stabbing its driver, who remained in the hospital this morning.

Moments later, he ran down a pedestrian at Ocean Avenue and Avenue T. That man later died.

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