At least 12 people have died and 23 are missing after a devastating forest fire in Los Gallardos in Spain’s southern Almeria province, public broadcaster RTVE reported Friday.

The fire, described by the regional government as the “worst” in Andalusia in terms of consequences to date, has burned more than 4,000 hectares (9,883 acres) of land, according to Andalusian President Juanma Moreno.

Four people are in critical condition and were transported to the Virgen del Rocio Hospital, while four others suffered less serious injuries, said officials.

The fire broke out Thursday in a roadside ditch, possibly linked to a damaged power line, although the cause remains under investigation.

Strong winds, with gusts exceeding 50 kilometers per hour (31 miles per hour) in some areas, caused the flames to spread rapidly through extremely dry terrain following recent heat waves.

The victims were found in a hamlet of the neighboring municipality of Bedar, with some discovered inside vehicles engulfed by the flames.

Antonio Sanz, Andalusia’s acting minister for health, the presidency, and emergency officials, described the blaze as “the fire with the greatest consequences to date” in the region and called it an “unprecedented tragedy”.

Authorities raised the region’s wildfire response plan to the emergency phase as the fire continued to spread, while Spain’s Military Emergency Unit (UME) deployed 150 personnel to reinforce firefighting efforts.

Read: Forest fire kills at least 12 in southern Spain

The fire and heavy smoke also forced the closure of two major roads in the province.

Separately, around 1,000 people were evacuated as a precaution due to another forest fire that broke out Thursday in the southern province of Malaga. The fire remains active, with nearly 180 personnel continuing efforts to stabilise the blaze.