A 45-year-old man was killed and three of his relatives — including a baby boy — were injured when a fire ripped through their apartment in The Bronx, authorities said Tuesday.

The blaze broke out on the 24th floor of the 26-story high-rise on Ogden Avenue near West 166th Street in Mount Eden around 10:15 p.m. Monday, authorities said. 

The man was discovered unconscious inside the apartment and rushed to Lincoln Medical Center, where he was pronounced dead, cops said. 

An 11-month-old boy, a 15-year-old boy and a 46-year-old woman were taken to Harlem Hospital, where they were listed in stable condition. 

All of the victims are members of the same family, though their exact relationship was not immediately known. 

The fire was placed under control in less than an hour. The cause of the blaze is under investigation by the fire marshal, officials said. 

Twenty-five FDNY units, including 106 firefighters and EMS workers, responded to the inferno.

Hours later, one person was seriously hurt in a fire on Fenimore Street near Nostrand Avenue in Prospect Lefferts Gardens, Brooklyn, the FDNY said. 

That blaze broke out around 3 a.m. Tuesday on the top floor of the two-story private home, officials said. 

The victim was taken to the Kings County Hospital Center in serious condition, an FDNY spokesman said. 

Firefighters encountered a heavy clutter condition in the home as they worked to knock down the flames. 

The fire was under control in less than an hour. 

Fire marshals will determine the cause of the blaze.