Two brothers who were 10 years old and younger drowned after falling in the Little Thompson River in Pinewood Springs outside of Lyons Sunday.
The children were found unresponsive by water rescue officials at around 12:30 p.m., Larimer County Sheriff's Office spokesman Bobby Moll said.
Crews performed CPR on both children, but were unable to revive them.
"Today's Mother's Day and anytime that a life is taken, whether it's a child or an adult or anything, its unfortunate," said Moll.
There was nothing unique about the water levels before the incident, Moll said, adding that officials are not seeing any surface runoff yet, though the water is swift in some spots.
Those living near the river said the stretch of river above where the children were found, known as the tubs, is a popular spot for locals to spend time, but is very dangerous because of the steep terrain and swirling water.
The Little Thompson River is located near the Boulder/Larimer County line.