The horrific Hamilton Heights fire that left one 15-year-old girl dead on Monday was caused by an overloaded extension cord, according to the FDNY.

The massive 4-alarm blaze tore through the six-floor building at 512 West 136th Street, sparking just before 5:45 p.m. 15-year-old Melisa Mendez, who lived in the building with her family, was killed, 11 others were injured, and about two dozen families were displaced.

FDNY officials have determined that the fire started because of the overloaded cord. "Last night’s fire started because of an extension cord, a power strip that was overloaded that was underneath furniture. This is nothing new to the Fire Department," Fire Commissioner Dan Nigro told the Post.

Fire officials say this is a common problem in older homes. Most recently, in January, newlywed Daniel McClung was killed and his husband injured in a massive fire in Hell's Kitchen, thanks to an overloaded cord. "You build up too much resistance. There’s too much electricity going through too small a wire. It may not trip a circuit breaker, but this will start to overheat and melt,” FDNY Capt. Kevin Anderson told CBS 2.

The FDNY warns [pdf], "Extension cords are only for temporary use. Most cannot carry
as much current as permanent wiring and tend to overheat. Overheating can occur at the plug, at the socket or over the entire length of the cord." Extension cords should never be used for "large current appliances such as refrigerators, freezers, air conditioners, clothes dryers or space heaters."

Officials also noted that Monday's fire likely spread when the tenant in the apartment where the blaze originated fled without closing the door. "We cannot stress enough and we have in the past forgotten this lesson, but folks forget it all the time: If you’re leaving the apartment, close the door," Nigro said. “The fire quickly spread to the hall, it quickly spread upstairs, and that was the cause of the loss of life.”