The robbers approached the family in the pretext of offering help after they pulled over their car at Parlikkad in the wee hours to fix their vehicle's wiper, police said.
The duo later threatened them with an iron rod, looted their valuables including money, jewellery and mobile phone before fleeing in their two-wheeler.
"Two persons came in a motor bike and asked us what happened.. They also offered to help us.. Suddenly, one of them asked us to give them whatever valuables we had," Vinod, a native of Palakkad district, told TV channels.
A manhunt was on to nab the robbers, the police said adding night patrolling would be intensified on highways to prevent such crimes.