NOWSHERA, Pakistan — Flooding in Pakistan killed more than 800 people in a week, a government official said Saturday as rescuers struggle to reach marooned victims and some evacuees show signs of fever, diarrhea and other waterborne diseases.

The flooding caused by record-breaking rainfalls caused massive destruction in the past week, especially in the northwest province, where officials said it was the worst deluge since 1929. The U.N. estimated Saturday some 1 million people nationwide were affected by the disaster.

The information minister for the northwest province, Mian Iftikhar Hussain, said reports coming in from various districts across the northwest showed more than 800 people had died due to the flooding. Many people remain missing.

Floodwaters were receding in the northwest, officials said, but fresh rains were expected to lash other parts of the country in the coming days.

In the Nowshera area in the northwest, scores of men, women and children sat on roofs in hopes of air or boat rescues.

"There are very bad conditions," said Amjad Ali, a rescue worker. "They have no water, no food."

A doctor treating evacuees at a small relief camp in Nowshera said some had diarrhea and others had marks appearing on their skin, causing itching. Children and the elderly seemed to have the most problems, Mehmood Jaa said.

Rescuers were using army helicopters, heavy trucks and boats to reach flood-hit areas, the U.N. said. It reported thousands of homes and roads were destroyed, and at least 45 bridges across the northwest were damaged.

The destruction is slowing the rescue effort, said Luther Rehman, a government official in Khyber-Pakhtoonkhwa, the northwest province. He said more helicopters and boats are needed.

Qamarul Zaman, the head of the Pakistan Meteorological Department, said no more rain was expected in the next few days for the northwest and that floodwaters there were receding. But Punjab province in the east, Sindh province in the south, and Pakistan's side of the disputed Kashmir region all could expect heavy rain over the next three or four days, he said.

A plane crash that killed 152 people in Islamabad on Wednesday occurred during stormy weather.