Police fired a Taser at a naked Brooklyn man armed with only a fluorescent light tube yesterday, sending him falling to his death from a second-floor ledge after he went on a 40-minute rant.

Iman Morales’ mom begged cops not to hurt her son, telling them he’s sick – then watched in horror as he plunged from the top of the roll-down gate on which he’d been perched.

An Emergency Services officer, acting on the orders of his boss, fired at the 35-year-old man at around 2 p.m., as he waved the 8-foot fluorescent light tube, police sources said.

“His body froze up and he fell face-first,” said Sean Johnson, who witnessed the drama at 489 Tompkins Ave. in Bedford-Stuyvesant.

Morales, who crashed 10 feet to the pavement, died a few hours later at Kings County Hospital.

Asked if police followed the proper protocol for using a Taser, NYPD spokesman Paul Browne said, “That’s being reviewed.”

A New York Police Department lieutenant was stripped of his gun and badge, and the officer who used the stun gun on the man was placed on administrative duty Thursday, officials said.

Amid his mostly unintelligible rant, Morales was heard yelling, “You’re going to kill me. I’m going to take everyone with me.”

He also screamed, “I’m going to die. You’re all going to die with me.”

Morales first emerged hanging out a third-floor window after a blowup with his mother at around 1 p.m., witnesses said.

Twenty minutes later, he climbed the fire escape to the fourth floor, where he tried to force his way into a neighbor’s apartment.

“He tried to come into my window and I ran out,” said 40-year-old Tonya Wright.

“He said, ‘Let me in.’ I told him, ‘I’m not letting you in.’ ”

Morales then headed to the second floor and screamed to the crowd, which included his frantic mom.

“She was saying, ‘No! No! Don’t hurt him. He is sick,’ ” Wright said.

With police shouting for him to get down, Morales made his way to a ledge above a the gate.

“Walk down now! Move down!” the police can be heard shouting to him on video.

He then picked up the light tube and waved it in the air before jabbing cops who had climbed out of the windows above.

“When he was poking the cop, people were laughing,” Johnson said.

He refused orders from the officers and continued his incoherent tirade.

Finally, one of the ESU cops on the street shot him with the Taser.

“He just fell face first,” said witness Sean Brown. “People were screaming and yelling. It was wrong.”

It was unclear what set off the episode, but, said Johnson, “once he started hitting the cop with that pole, that’s when it turned serious.”

Morales had one prior arrest, for a Manhattan petit larceny.

“This is very out of character,” said the building’s superintendent, Charlene Gayle, 31.

“Nice guy, clean cut, well kept, never irrational. Didn’t have irrational behavior.”

Additional reporting by Larry Celona

john.doyle@nypost.com