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DALLAS (CBSDFW.COM) - The calls came in from Rockwall, McKinney, Cedar Hill and Irving as many North Texas residents were stunned by an early morning flash that light up the pre-dawn sky.

It was a mystery in the sky as several people witnessed a big 'blueish-green' flash in the sky at around 6:30 Monday morning. Many residents said it looked like it was in Eastern Dallas County.

According to Oncor, the bright light was from a transformer malfunction at a substation in Mesquite.

Several hundred people were without power until around 7:30 a.m.

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