Several fire fighters are also reported to be injured.
The fires began on Saturday during an intense heatwave and rainless thunderstorms, with temperatures of more than 40C (104F) in some areas.
Portugal's Secretary of State for Internal Affairs Jorge Gomes said that at least 16 people were killed in their cars on the road between the towns of Figueiro dos Vinhos and Castanheira de Pera. Numerous victims were trapped in their cars as flames swept over a road, reported The Inquirer.
No information has yet been given on how the others were killed.
However, since that report, AP has tweeted the latest figures as reaching 62 dead, as Portugal announces three days of mourning in the country.
There were very particular circumstances with the lightning strikes here - this fire started with a dry lightning strike.
The fire, which has yet to be controlled, is already one of the deadliest forest fires in Portugal in decades. Our thoughts are with victims.
Six firefighters are among those injured.
Many world leaders, including French President Emmanuel Macron, Pope Francis and Indian Prime Minister Narendra Modi, expressed solidarity with Portugal.
He referred to the "devastating fire" at the end of his Sunday prayer, delivered from his studio window overlooking St Peter's Square in the Vatican.More news: Garry Monk named as new Middlesbrough manager
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"Solidarity with Portugal, hit by awful fires".
Portugal's team is in Russian Federation, where it is set to start the Confederations Cup later on Sunday against Mexico. Authorities say that at least 30 people died along the densely forested roadway as they tried to escape.
The European Commission's aid chief, Christos Stylianides, said in a statement that "all will be done to assist the authorities and people of Portugal at this time of need".
France and the European Union have also offered aircraft.
A wildfire swept through central Portugal on Saturday, killing more than 60 people and injuring dozens more in what the country's prime minister called "the biggest tragedy of human life that we have known in years".
Avelar resident Isabel Brandao blamed it on the lack of rain. "If it had rained, this would not happen".
"We're doing everything we can to see if we can mobilise fire crews from Lisbon".
"What happened was cables and communications towers were destroyed by the fire, even their first replacements melted", he said.