At least 33 people have been killed by heavy flooding in central Nigeria's Plateau state, relief official Abdussalam Muhammad has told the BBC.He said the floods had destroyed homes and washed away roads and bridges, hampering rescue efforts.More than 12,000 people were affected by the heavy rains in six districts, including Shendam.Flooding killed more than 39 people last month near the state capital, Jos.Officials have warned of more flooding in the coming days.The rainy season in Nigeria typically runs from March to September.Mr Muhammad, the co-ordinator of the National Emergency Management Agency in central Nigeria, said hundreds of people were left homeless by the floods.They desperately needed aid, but it was difficult to reach them because roads and bridges had been destroyed, Mr Muhammad added.The Shendam district was worst affected by the floods, along with areas such as Wase and Kanam.