Portugal on Monday is struggling to control the deadliest wildfire in its history, which has devastated the central region of Leiria since Saturday, with preliminary numbers of casualties estimated to be at least 61 dead and 62 injured.

The fire, which began on Saturday afternoon, ignited in the municipality of Pedrogao Grande, in the central region of Leiria, a huge plain with small villages crisscrossed by several national roads.

"The dimension of this fire was such that we don't have memory of such a human tragedy," said Portuguese Prime Minister Antonio Costa at the emergency command post in Pedrogao Grande.

Costa warned the death toll could increase, adding that there are currently more than 700 emergency staff deployed to tackle the fire along with air support from Spain and France.

The forest fire broke out on a road linking the municipalities of Figueiro dos Vinhos and Castanheira de Pera, causing people to be trapped on a road surrounded by flames.

According to a press statement by the Internal Administration department, 30 people are reported to have died in their vehicles on this road, including entire families.

Another 17 bodies were found along the side of other roads, while 10 more were recovered in the rural areas surrounding these roads.

Among those injured, four are in serious condition, and damages to several homes nearby were reported.

The Judicial Police (PJ) told Efe that the police has ruled out arson and pointed to lightning striking a tree as the most likely cause of the deadly fire.

Strong winds together with temperatures above 40 degrees on Saturday caused the fire to spread rapidly, hindering the work of firefighters.

The fire remains active in four areas, two of them are considered out of control, according to the department.

The Government has sent some 400 personnel from social services to attend to the affected people in the area and ordered an emergency evacuation of people residing in nearby areas.

In addition, the search and identification of possible victims are carried out village by village. All available means of assistance have been mobilized towards Leiria, including four fire fighting aircraft sent from Spain.

The Portuguese government has declared three days of national mourning, starting on Sunday, Jun 18.

"It is a time of pain but also ... a time to carry on the fight," the president of Portugal, Marcelo Rebelo de Sousa said in a televised message addressed to the nation, where he also expressed his "endless thanks" to the emergency services for tackling the blaze and rescuing those affected by the incident.