BRASILIA, Brazil (AP) — Brasilia, Brazil’s modernist capital, woke up the last two days to find its iconic buildings enveloped in smoky air. The central part of the country is just the latest region affected by smoke from fires in the Amazon rainforest, Cerrado savannah, the Pantanal wetland and the state of Sao Paulo. The smog crisis prompted President Luiz Inácio Lula da Silva to visit Brazil’s national fire monitoring center in Brasilia on Sunday afternoon.

“No fires caused by lightning were detected. This means that people are setting fires in the Amazon, the Pantanal, and especially in the state of Sao Paulo,” he said. His government pledged to step up firefighting and investigations to identify the culprits.

Fire alerts so far this month total almost 3,500 in southeastern Sao Paulo state — the most registered in any month since data collection began in 1998. Over half those fires occurred on Aug. 23, raising the suspicion of a coordinated attack.

The smog caused 48 cities to declare a red alert. The good news was that a cold front Monday brought declining temperatures and rain, extinguishing all fires, the state government said. In Brasilia, the air quality index reached a very unhealthy level on Sunday night, according to Brasilia’s environment institute.

This is the first time the state agency has recorded a smog alert since its creation in 2007. Public events were canceled, and the airport of the nearby city of Goiania was closed for a few hours. Amaz.