Severe thunderstorms sent normally placid streams over their banks across the Denver area, sweeping away a 2-year-old boy in a stroller and a teenager who was trying to help with a rescue. Both were still missing Tuesday, police said.

The toddler's mother had been out for a stroll Monday along a bike path that follows a creek near downtown. It had been a sunny morning, and the thunderstorm developed quickly. In less than an hour, it dumped more than an inch of rain, flooding streets and sending a torrent of water down the tiny creek.

The woman sought refuge under a bridge as hail started to fall but realized she needed to leave the path, Denver Fire Department spokesman Phil Champagne said.

"Once you enter (the bike path), you're in a chute," Champagne said. "She knew she was in trouble and was trying to get out. She was on the phone with her grandfather, trying to figure out a way out.

"The water knocked her down, she was dragged for a little bit and was unable to hold onto the stroller," Champagne said. "What a tragic event. That poor mother to see her child swept away like that."

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Firefighters struggled against the current to rescue the woman, but her son and stroller were swept downstream. The stroller was later found empty more than a mile away in the South Platte River, Champagne said.

Firefighters sent two divers to reach the mother as she clung to a concrete embankment.

When she realized firefighters did not her son, she apparently released her grip and drifted downstream, where other firefighters pulled her from the water, Champagne said.

In south Denver, a police officer and firefighters were able to save one teenager from a swollen creek in a park, but another teen who apparently was trying to help was swept away and remained missing, Champagne said.

Rescuers searched Tuesday for the 2-year-old, believing he could have become stuck in the eddies of the South Platte River. A search for the teen was expected later.

The officer was hospitalized with what appeared to be hypothermia, police spokesman John White said. The missing baby's mother was also hospitalized. Their names were not released.