A 52-year-old woman died on Wednesday morning after the vehicle she was travelling in crashed into a tree on Embu-Kubugu road.
Three others sustained multiple injuries and were rushed to Embu Level Five Hospital.
Area police boss Mark Wanjala said the driver of the Probox lost control and veered off the road before crashing into the tree.
He said the road, which is under construction, has become a death trap as accidents are reported on a daily basis.
Wanjala asked drivers to be vigilant, avoid speeding and look out for loose chippings that make vehicles skid when brakes are applied.