Residents in Brazil'snortheastern state of Pernambuco were bracing for more days of heavy rain after at least 91 people were killed as downpours triggered floods and landslides, according to the Civil Defense, CNN reported.

A further 26 people are still reported missing, said the Civil Defense on Twitter.

The state governor, Paulo Câmara, said that many more people could be unaccounted for.

Brazilian President Jair Bolsonaro spoke to the press after visiting the area on Monday.

"Unfortunately, these catastrophes happen," Bolsonaro said during a press conference, saying "similar problems" happened before in other cities affected by heavy floods.

"We flew over the affected area, tried to land but, following recommendation from the pilots, decided not to due to inconsistency of the soil," Bolsonaro told reporters, according to CNN.

Since heavy rains began on Wednesday, nearly 4,000 have lost their houses, according to CNN Brasil. Fourteen municipalities have declared a state of emergency. 

The Pernambuco civil defense has urged residents living in high-risk areas around the city of Recife to seek shelter elsewhere after the rain caused landslides there. Schools in Recife have opened to shelter displaced families.

Brazil's northeast has been suffering from exceptionally high volumes of rain, officials say. Some areas have registered more rain in a 24-hour period over the weekend than the total volume expected for the month of May. 

Some parts of the state had a reprieve from the rain Monday as showers moved toward the coast, but Pernambuco is forecast to get another 30-60 mm of rain in the next two days, while isolated areas could see over 100 mm. The region could experience more than half a month's worth of rainfall in just four days, between Saturday over the weekend until the end of Tuesday, CNN reported.

Gusts -- which can lead to power outages and falling debris -- could also be as high has 100 kph.

The weekend downpour triggered the fourth major flooding event in five months in Brazil, according to a Reuters report, which highlighted a lack of urban planning in low-income neighborhoods throughout much of the country. Favelas -- slums or shantytowns -- are often erected on hillsides prone to giving way, usually outside major cities.

In December, downpours caused two dams to burst in nearby Bahia state, killing dozens and submerging entire streets, according to CNN.