
They were scheduled to take an exam at the provincial university in the morning.
A five-page leaflet was found at the scene of the killing, warning government officials not to "hurt" the local Muslim population.
Meanwhile, a local academic said statistics showed insurgency-related incidents in the Muslim-majority region were on the rise, with the brutality only getting worse.
Assoc Prof Srisompob, director of Prince of Songkhla University's Deep South Watch Centre, said the insurgency had become worse since January, in terms of both the frequency and the violence of incidents.
He said the attacks were having a psychological impact on residents, many of whom had no hope that the authorities would restore peace in the deep South and were too scared to cooperate with officials.