18 dead and a million evacuated as deadly typhoon hits China
Fourteen people were also missing after a landslide was triggered by the storm, state media reported.
Lekima made landfall in the early hours of Saturday in Wenling, between Taiwan and China's financial capital Shanghai.
The storm was initially designated a "super typhoon", but weakened slightly before landfall - when it still had winds of 187km/h (116mph).
The fatal landslide happened in Wenzhou, near where the storm made landfall, state media said. It occurred after a barrier lake - or natural dam - formed, pooling water from the heavy rains before collapsing.
Lekima is now slowly winding its way north through the Zhejiang province, and is expected to hit Shanghai, which has a population of more than 20 million.
Emergency crews have battled to save stranded motorists from floods. Fallen trees and power cuts are widespread.