Brazilian presidential candidate Eduardo Campos has died aged 49, after his private jet encountered bad weather and crashed into houses in the coastal city of Santos on Wednesday.
The six other people travelling with Campos were also killed, as well as at least four people on the ground, according to local reports.
Air Force officials said that air traffic control lost contact with the 12-seater Cessna 560Xl jet after it could not land in Guaruja, having been confronted with cloudy, rainy weather.
It then crashed in the south-eastern city, 43 miles east of Sao Paulo, according to city hall officials in Santos.
Television footage from the scene showed the wreckage of the plane smouldering among smashed buildings in the residential neighbourhood.
The Brazilian Socialist Party (PSD) leader was governor of Penambuco state before announcing he was running for president in the 15 October elections. He was third in opinion polls. Previously he had served for 20 years as a state then federal congressman.
Video: Presidential candidate dies in plane crash
In light of the opposition leader’s death, Brazilian President Dilma Rousseff has cancelled all campaign activities for three days, Rousseff's Workers' Party said, ahead of the presidential election on 5 October.
Rousseff is leading in polls with about 36 per cent of voter support, while Senator Aecio Neves has enjoyed about 20 percent support and was widely expected to face Rousseff in a second-round runoff.
Campos, a former governor of northeastern Pernambuco state, was running as a business-friendly leftist and had strong support from many banks and industrial groups.
On Tuesday night, Campos had been in Rio de Janeiro for an interview with the country's most-watched nightly news program. Several pundits praised his performance as confident and authoritative, and said he might rise in polls as a result.
His death could see Marina Silva, his running mate, become the Brazilian Socialist Party's candidate. She placed a strong third in the 2010 presidential election and enjoys robust support from young voters and evangelical voters, but her pro-environment agenda means that many in Brazil's powerful agribusiness sector distrust her.
Additional reporting by agencies