According to local media, presidential candidate Eduardo Campos was killed when his private jet crashed in bad weather.
BBC News reports:
Mr Campos' plane was flying from Rio de Janeiro's Santos Dumont airport to Guaruja airport outside Sao Paulo when it hit bad weather, aviation authority spokesman Pedro Luis Farcic said.
In regards to the likely consequences of Campos' death, Reuters notes:
Campos, 49, had the support of about 10 percent of voters in recent polls. His death, if confirmed, will likely lead the two other leading candidates, President Dilma Rousseff and Senator Aecio Neves, to pause their presidential campaigns for a period of mourning just as the run-up to the Oct. 5 election was starting to capture the public's full attention.