A trailer truck lost control on a downhill road in Prachin Buri Saturday evening, killing four and injuring 15 others, police said.
Police said the truck driver fled the scene following the accident on the Highway No 304 in Nadee district at around 6 pm.
The truck crashed into two passenger vans, a pickup-truck, a sedan car and a big bike.
Police suspect the truck driver was speeding down the hill, causing the brake system to malfunction before it swept the five vehicles.
The four killed victims were identified as Chaiphat Latthikul, 42, Prayoon Srikhamthong, 32, an unknown man and unknown woman.