A 6-year-old Stamford boy is in critical condition this evening after nearly drowning at a local park yesterday. Police say the boy's older brothers were teaching him how to swim at Southfield Park, where swimming is prohibited. They say the victim went under the water and had trouble resurfacing. A 19-year-old lifeguard, who happened to be in the area, rushed over and gave the boy CPR to get him breathing again. Residents say the city needs to do a better job keeping swimmers from unauthorized areas. In response, officials tell News 12 Connecticut that warning signs are routinely stolen or vandalized, and that they do not have the funding to hire someone to lock the park gates every night.