Horrific video out of Houston last week showed us a deadly helicopter crash that claimed the lives of four people, including one child:

[Warning: Graphic, Language]

Now it turns out that faulty lighting on the tower might have been to blame:

Lighting on a Houston radio tower reportedly failed just days before it was hit by a helicopter on Sunday, killing four people in a fiery explosion that toppled the tower and left debris scattered through the neighborhood.

Operating as an air tour flight, the helicopter was flying at an altitude of 600 feet when it slammed into the 1,000-foot-high tower just before 8 p.m. Sunday, according to open-source data and investigating officials.

The tower's lights were "unserviceable" until the end of the month, according to a Federal Aviation Administration notice to pilots published last Thursday.

The "cause of the crash remains unclear," investigators report. Flight track data, meanwhile, doesn't appear to indicate anything erratic or dangerous about the flight itself prior to the crash.

Though it can be hard to tell, it appears that the copter may have struck the tower a little more than midway up:

The crash site was a burned-out circle on Monday:

😔

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