KLAS-TV reports the girl and her family were playing on the side of the river when she was sucked into an irrigation ditch at about 12:40 p.m. on Tuesday.
Two other children were also endangered, but their grandmother was able to pull them out.
The three-year-old went into the water near the Riverside Road bridge that connects Mesquite to Bunkerville. That's about 80 miles northeast of Las Vegas.
Roughly 50 rescuers searched for hours hoping to save her.
Police tell KTNV-TV that the incident is a reminder to keep children safe around all bodies of water.
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