A couple and their grandchildren were killed when their motorcycle collided head-on with a pickup truck in Pha Khao district of Loei on Friday evening, police said.
The fatal collision occurred on a road in front of Debsirin Pattana temple in tambon Non Po Daeng around 5pm, Pol Maj Diao Khamhaengpol, an investigating officer at the Pha Khao police station, said on Saturday.
Police and rescue workers at the scene found a man identified only as Kaew, 57, his wife Boonkong, 53, their 3-year-old granddaughter and 11-month-old grandson lying dead next to the white Honda Wave motorcycle and the black Nissan Navara pickup truck.
The pickup truck driver, Satapol, 29, suffered serious injuries and was admitted to Pha Khao Hospital. Their surnames were withheld by police.
Witnesses told police that the pickup was travelling at high speed, causing the vehicle to veer out of its lane and hit the motorcycle in the opposite lane. Both the pickup and the motorcycle were badly damaged.
Police said the couple and their grandchildren had been travelling to a market to buy milk prior to the crash.
Police are still waiting to question the injured pickup driver.