One protester has been shot dead and another seriously wounded at the site of a blockade in southern Thailand where rubber farmers have been protesting for more than a week against a steep decline in rubber prices, AP reported. It wasn't immediately clear who was behind the shooting, which occurred before dawn Sunday near a railway crossing the farmers have blocked along with a major road in Nakhon Si Thammarat province. Police say they believe the attack stemmed from a quarrel among the protesters' own security guards, whom they say carry weapons and get into fights frequently. Police denied rumors circulating among some of the protesters that authorities staged the attack. The protesters are calling for the government to guarantee the falling price of rubber to help increase their incomes.