A noxious cloud of smoke is spreading across the city of Guarujá, close to Brazil's largest port of Santos, after an overnight chemical explosion in a coastal warehouse operated by logistics company Localfrio.

As many as 16 tanks containing chloric acid and sodium dichloroisocyanurate, a disinfectant, caught fire after rainwater leaked into the storage facility where the tanks were being held, according to the BBC. Municipal officials declared that the fire is now under control, but the smoke is still permeating the area. Firefighters are focusing on stopping the gas leak and have been trying to smother the fire without using water, since rainwater caused the explosion in the first place, explains TeleSUR.

Mariela Braga, a Localfrio spokeswoman, stated that emergency measures were in place, including the evacuation of the immediate vicinity. She also said the gas was toxic, but "not that toxic," the Associated Press reports.

Experts disagree with the company's statement, however. "It is an extremely toxic product. It irritates the skin and eyes and if inhaled will also irritate the lungs," said medical toxicologist Flavio Zambrone, according to the AP.

At least 66 people have been taken to hospital for breathing issues, and Guarujá Mayor Maria de Antonieta de Brito has urged residents to remain at home or cover their faces with cloth when they go outside because the gas can cause skin irritations, burning sensations, breathing problems and fainting spells, Reuters explains.

This is the latest in a series of industry-related chemical accidents with deep environmental implications to happen in Brazil. Fires at the port of Santos occured in 2013 and in April 2015 when a fire at a fuel storage unit sent columns of thick black smoke into the air for nine days, as Reuters reported at the time. In November of last year a mining-related dam collapse in the state of Minas Gerais caused a massive toxic mudslide that buried villages and contaminated river water supplies. The accident has led to recent charges by the Brazilian government against the companies involved, suing them for environmental crimes.

Santos is Brazil's main commodities exporting port and the largest in Latin America. It is situated just 49 miles from São Paulo, the largest city in the southern hemisphere, according to the Latin Correspondent.