A massive forest fire in central Portugal has killed more than 60 people, many trapped in their cars while trying to escape the flames, and injured dozens more, officials said.

Hundreds of firefighters are battling the huge fire that Portuguese officials believe may have been sparked by lightning.

Prime Minister Antonio Costa called it "the greatest tragedy we have seen in recent years in terms of forest fires," the BBC reported.

Costa warned that the death toll could rise as the search for the missing continued Sunday.

Thirty bodies were found inside cars and almost 20 more were found next to vehicles, Portuguese officials said. Most died from smoke inhalation and burns.

Authorities have declared three days of mourning starting on Sunday.

The Associated Press contributed to this report.