The first explosion injured six army rangers patrolling a local road in Narathiwat province, the Bangkok Post reported.
The second blast occurred as police forensic and bomb disposal units were inspecting the site of the first blast.
Two police officers and five journalists were injured by the second bomb, which had been suspended in a tree about 110 yards away.
All of the injured were taken to a hospital. Three of the rangers were in critical condition, said a local chief.
None of the reporters were believed to have been seriously injured.
A 10-year-old conflict with a separatist group has caused the deaths of more than 5,700 people in three of Thailand's southern provinces.
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