The deputy was found just before 2:30 Thursday morning near the Hockley Community Center.
Officials say the Good Samaritan found the deputy breathing but unresponsive and immediately got on the radio yelling in Spanish for help.
Officials say after some confusion, they got a Spanish-speaking deputy on the radio to communicate with the Good Samaritan and figure out what was happening.
Precinct 4 and EMS responded and decided it was best to airlift the deputy to the hospital.
Precinct 4 identified the victim as 57-year-old Deputy Constable William Bell. They say he suffered an apparent stroke while he was on duty in Hockley Park.
Bell was on assignment to protect senior citizens in the area who went to attend the Houston Livestock Show and Rodeo by bus. Bell was locking the park gates when he suffered a stroke.
The Good Samaritan found the deputy on the ground in distress when he radioed for help.