Rains started late on Thursday and continued into Friday, causing floods that cut off roads, destroyed bridges and triggered landslides in the city of at least 6 million people. "Until now, the toll is at 30 identified dead. Others are wounded. Some houses are damaged. Many were completely destroyed," said Saleh Kinyongo, spokesman for Congo's Ministry of Humanitarian Affairs.
He said some victims were electrocuted when power cables fell into standing water during the storm. Others were crushed when their homes collapsed during landslides.
A Red Cross official earlier told Reuters three people had been killed by lightning.
The region surrounding the vast country's capital is entering its annual rainy season, when daily downpours cause regular and often deadly floods.
Kinyongo said Kinshasa's municipal authorities had begun reopening roads on Friday. He said the Ministry of Humanitarian Affairs was setting up a crisis commission to deal with those made homeless by the storm.