A 10-vehicle chain collision occurred on the AMJ highway in Cheng, Melaka, around 9 p.m.
An 11-year-old boy is in critical condition and intubated, while his father suffered a broken leg.
Initial investigations indicate the driver of a Toyota Hilux lost control and rammed into vehicles stopped at a traffic light.
Authorities have seized dashcam footage and are conducting toxicology tests on the Hilux driver as part of the ongoing probe.