A shoeless madman was charged Thursday with murder for allegedly stabbing another straphanger to death in an unprovoked spurt of violence on a Queens train – as harrowing video of the bloody attack shows terrified riders scrambling off the subway car.

Jyrell Thomas, 25, allegedly whipped out a knife and plunged it into Mesias Lojano, 59, without warning – stabbing him three times in the torso and once in the neck – on board the packed southbound J train approaching Woodhaven Boulevard around 5:20 p.m. Wednesday, police and sources said.

The gravely wounded Lojano, of Ozone Park, was rushed to Jamaica Hospital Medical Center, where he later died, police said.

Disturbing video posted by a straphanger to Facebook shows panicked commuters frantically fleeing the rush-hour train – where a shoeless Thomas is seen knifing Lojano repeatedly while he’s on the ground of the subway car, near its doors.

The victim tried to shield himself from the blade – with his hand covered in blood as the callous stabber pulled him by his hoodie out of the car, left him on the platform and then ran off.

The knife-wielding attacker then rushed down the stairs of the elevated station – behind other commuters including a mother and child – as the witness filming the incident yelled in English and Spanish for someone to grab the weapon.

A group of men, including the person filming, then ran after the suspect – who sprinted out into the street and finally perched himself on a garage roof, before police cuffed him.

Thomas – a Bronx resident who did not know Lojano – was also charged with criminal possession of a weapon and hospitalized, according to police, though it was not clear why.

The deadly violence initially appeared to have stemmed from a dispute, but police confirmed Thursday the attack was unprovoked.

Thomas has one previous arrest from early September – for allegedly stealing $23 worth of merchandise from a Bronx Target store and then attempting to flee from cops, according to cops and sources.

He was charged with petit larceny, obstruction of governmental administration and criminal possession of stolen property, the sources said.