Emergency services battling to stop a reservoir dam in central England from collapsing brought in new pumps Saturday to reduce the water levels, as more storms were forecast.

Hundreds of people have been evacuated from the Derbyshire town of Whaley Bridge, after part of the dam holding back the Toddbrook Reservoir above them collapsed following heavy rain.

The Met Office weather centre warned of further downpours and thunderstorms in the area on Sunday.

During a visit on Friday evening, Prime Minister Boris Johnson described the dam wall as “dodgy but stable”, but said the 180-year-old structure would require a “major rebuild”.

A Royal Air Force Chinook helicopter has been dropping bags of aggregate onto the section of the dam spillway which was damaged on Thursday after heavy downpours.

A police spokeswoman told AFP that extra pumps were being put in on Saturday as officials raced to bring the water level down in the reservoir.

After two nights out of their homes, some locals were allowed back briefly on Saturday to collect any essential items — and family pets — but warned that there remained a high risk to life in the area.

A British military helicopter dropped sacks of ballast onto the outer slope of a reservoir dam in central England on Friday in an effort to prevent it from collapsing and flooding the town below.

Police were evacuating more than 6,000 residents of Whaley Bridge, telling them to take pets and any medication they needed with them after the dam was badly damaged during heavy rains.

Prime Minister Boris Johnson visited the area on Friday evening, meeting affected residents and emergency services. “I flew over the dam and it looks pretty scary,” he said.

Officials said the dam, holding back 300 million gallons of water, was in danger of failing, putting lives at risk.

“The structural integrity of the dam wall is still at a critical level and there is still a substantial risk to life should the dam wall fail,” the assistant chief constable of Derbyshire police, Kem Mehmet, told a news conference.

Agencies