Araujo said the Brazilian army has sent more than 500 soldiers to aid the rescue effort and that shelters for those affected had filled up.
"In only three hours it rained as much as we are used to seeing in two months," Odileida Sampaio, the mayor of Altamira in the state of Para, was quoted by the official Agencia Brasil news agency as saying.
Luiz Inacio Lula da Silva, the Brazilian president, flew over the hardest-hit areas on Tuesday, delivering food baskets to shelters and meeting local officials.
Silva promised aid to repair infrastructure, and voiced concerns that global climate change could be responsible for the unusually heavy rains and destruction.
More rain is expected in the north in coming weeks, officials said.