Sodium cyanide, a highly toxic chemical, can kill if swallowed or inhaled in small amounts and poses a major environmental risk, health officials warned. After the lorry overturned late on Saturday, several containers were taken by people who rushed to the scene.
The government urged people to avoid the site on the busy Nairobi-Nakuru highway, while the US embassy advised its citizens to take a detour. The accident occurred about 35km (22 miles) from Nairobi, causing a spillage on the tarmac.