Four gunmen on motorbikes opened fire on Somchai Chuanchomphu and Muhammad Reswan Maray as they were riding from their base at Wat Cheongkhao to a market in Ba Cho district, according to police.
Somchai was declared dead at the scene while Muhammad was rushed to hospital.
Violent incidents have taken place on almost a daily basis in the predominantly Muslim region since early 2004, killing about 7,000 people so far. Police said the fresh gun attack on the two rangers was the latest in a spate of violence.