The incident occurred at around 10.30 am on the southern gateway route to the Central Highlands resort city. The landslide site was located about 2 km from the foot of the pass and roughly 200 metres beyond Datanla Bridge.
Soil and rocks slid from a steep roadside slope, sending a multi-tonne boulder close to the centre of the roadway.
Authorities were dispatched to manage traffic and clear debris from the road surface. The boulder was too heavy to be removed manually and required specialised machinery.
The affected slope lies about eight metres above the road and borders a pine forest. Local officials said signs of ground subsidence had been observed along a stretch of the upper slope, raising concerns about further landslides.
Several hazardous landslide-prone areas remain along Prenn Pass following the 2025 rainy season and have yet to be fully stabilised, according to local authorities.