Sierra Leone mudslide leaves more than 300 dead and at least 700 missing An estimated 3,000 people had their homes swept away in the disaster.

 -- At least 312 people have been killed and 700 others are missing in the wake of heavy flooding and mudslides in Sierra Leone, a Red Cross spokesperson told ABC News. An estimated 3,000 people had their homes swept away in the disaster, and those numbers could still rise, the Red Cross said.

A hillside on the outskirts of Sierra Leone's capital Freetown collapsed Monday morning after a night of heavy rain, sweeping away houses and turning roads into rivers. Many people were asleep at the time of the landslide, which happened around 6:30 a.m. local time, and aid organizations fear that many may still be trapped in their homes.

“In places, entire communities seem to have been washed away and whatever is left is covered in mud,” Abdul Nasir, program coordinator for the International Federation of Red Cross and Red Crescent Societies, said in a statement.

The Red Cross said that its volunteers have rescued 71 people from the mud and rubble so far.

“Although a full picture of the damage is still emerging, reports indicate that the situation in and around Freetown is extremely serious,” Alex Carle, director of international programs at the British Red Cross, said in a statement. “At least a hundred houses have been affected, some of which have been completely submerged."

He added that he is concerned about the increased risk of waterborne diseases such as cholera and typhoid after the flooding.

Save the Children said that one of their staff members and his young children are among the missing. His house was buried during the flooding.

“We were driving on the main road out of Freetown past Regent when a lady ran onto the road and started gesticulating wildly. She called out to another lady who had been riding a bike in front of us who, after a brief conversation, started crying and looked very upset,” Ramatu Jalloh, a worker with Save the Children who was near the scene of the flooding, said in a statement.

“It was clear from their reactions that something terrible had happened. Soon afterward, another man ran towards our car. He was crying about the number of lives that had been lost," Jalloh added.

Dozens of children are likely to have lost their lives in the flooding, according to Save the Children.

The U.N. Secretary-General "is saddened by the deaths and devastation" caused by the mudslide, his spokesman said in a statement.