"Nineteen deaths have been confirmed, all of them civilians. Three of them died from smoke inhalation and 16 burned to death in their cars when they found themselves trapped by flames on the road from Figueiro dos Vinhos to Castanheira de Pera," Secretary of State for the Interior Jorge Gomes told journalists.
Gomes said that 14 civilians had been injured, 10 of them seriously, along with six firefighters. Two people remain unaccounted for.
The flames spread "with great violence", moving out in four directions, he said.
Several villages were affected by the blaze but Gomes was not immediately able to comment on the extent of the damage caused.
Portugal was sweltering under a severe heatwave yesterday, with temperatures exceeding 40 degrees Celsius (104 degrees Fahrenheit) in several regions.