NEW DELHI, June 2 (Xinhua) -- At least nine people have been killed and 12 others injured in rain-related incidents in the eastern Indian state of West Bengal, officials said Saturday.

"While five people died due to lightning strikes in the state's Hooghly and Birbhum districts in the past 24 hours, others died of wall collapses triggered by heavy rains that have lashed the state since Thursday night," a disaster management official said.

"Those who sustained injuries due to lightning strikes are being treated in various government hospitals across the state," he added.

Some 21 people were killed and more than 12 others injured in thunderstorms and lightning strikes in the eastern state of Bihar and the southern state of Andhra Pradesh Thursday night. Some of those injured are in serious condition.

Lightning and thunderstorms are common in India during the pre-monsoon months of May and June.