Security Minister Luis Cordero said the suspect used a liquid accelerant to start fires in a wheat field, with authorities seizing five liters (more than a gallon) of fuel from him.

He was arrested at dawn in the town of Perquenco in Araucania region, south of Biobio.

The fires began simultaneously on Saturday in various parts of Biobio and Nuble regions, about 500 kilometers (310 miles) south of the capital Santiago.

Fanned by strong winds and high temperatures, the flames quickly ripped through the coastal towns of Penco, Lirquen and Punta de Parra, leaving a blackened landscape of smoldering ruins.

Around 1,000 homes went up in smoke, affecting around 7,500 people.

Other fires were later reported further inland, in the Biobio town of Florida, about 40 kilometers east of the city of Concepcion and in Araucania.

Cordero said substances used to start fires, including plastic containers containing accelerant, were found in Concepcion.

Firefighters were still battling 35 blazes Wednesday -- 22 in Biobio, five in Nuble and eight in Araucania, according to national forestry officials.

A drop in temperature in recent days has helped ease the situation.

"We managed to reduce the intensity of the fire," Carlos Zulieta, a firefighter in Florida told AFP, adding that it was now advancing "more slowly."

The government said it would pay compensation of $700 to $1,500 to victims.

Aid began trickling into affected areas on Wednesday.

Municipal workers and private companies were delivering portable toilets and generators to Lirquen, where some families are camped out in the ruins of their homes.

In February 2024, wildfires broke out around the coastal resort of Vina del Mar, 110 kilometers from Santiago, leaving 138 dead.

Investigations revealed that firefighters and forestry brigade members started the fire, which spread rapidly due in part to high temperatures during the southern hemisphere's summer.