An Italian couple was killed when a tanker truck overturned and crushed their motorbike in Chumphon.
Giuliano De Santis, 42, and Ilaria Rizzo, 37, were driving on Pak Nam Road in Pak Nam Sub-district when the oil lorry lost control and crashed.
The Isuzu 10-wheeler overturned, spilling thousands of litres of fuel across the road.
The 64-year-old driver blamed bad brakes for the crash, insisting it was his first accident in 10 years of delivering petrol to gas stations around Chumphon.
A witness, however, claimed the senior citizen was speeding when he hit the intersection and tried to make a left turn, causing the vehicle to go up on two wheels and then topple.
He is being held pending further investigation.
The Italians had been in Thailand on holiday since Feb. 21.