Working fire crews have attended two incidents in the first hour of a strike by Fire Brigades Union (FBU) members.
FBU firefighters are on strike from 2pm until 2am tomorrow morning.
Crews attended a false alarm in Burnham and a road accident in Harlow, where a fuel spill was dealt with.
Essex County Fire and Rescue Service has warned people to be extra vigilant during the strikes.
The FBU will also be on strike in Essex from 10am to 3pm tomorrow, in protest against Government pension reforms.