A man drowned in a Colorado lake Wednesday when he tried to help four children swimming in rough waters.

According to Colorado Parks and Wildlife, the 53-year-old was on Sailboard Beach at yesterday afternoon when his children and their friends went into rough water. Park visitors said they saw the man go under the water and went to pull him out, while others called rangers for help.

The park rangers arrived on the scene within minutes. Authorities said witnesses, park staff, and medical personnel all assisted with CPR for around 40 minutes, but were unable to revive him. His body was turned over to the Pueblo County Coroner's Office for identification and to officially determine his cause of death.

Officials said the children are safely with their respective guardians.

CPW said the man was not wearing a life jacket, and the water temperature was in the upper 50s. They encouraged anyone planning to go into the water or out on a watercraft to wear life jackets and be aware of the dangers of cold water shock.

"Water below 68 degrees Fahrenheit is dangerous. Sudden immersion in cold water can cause gasping, inhalation of water and hypothermia, resulting in unconsciousness or swimming failure as muscles become numb," said CPW.

They also encouraged swimmers to , as heavy rain or snow melting in the mountains can cause water levels to rise quickly.