At least 93 people have been struck by lightning and killed in India over the past two days, disaster management officials said Wednesday, as annual monsoon rains swept the country.

Lightning strikes are relatively common in India during the June-October monsoon, which hit the southern coast earlier this month, but this week's toll is particularly high.

Most deaths occurred in the eastern state of Bihar, where an overnight storm killed at least 56 people and injured another 28, mainly in rural areas.

"The death toll has climbed to 56 and 28 are injured. Many of the victims are children and women," Anirudh Kumar, a senior official at Bihar's diaster management agency, told AFP.

Another 37 people were killed across Uttar Pradesh, Jharkand and Madhya Pradesh states, according to figures compiled by local disaster management authorities.

Prime Minister Narendra Modi tweeted that he was "deeply anguished" by the loss of life.

Lightning kills thousands of Indians every year, most of them farmers working the fields.

More than 2,500 people were killed by lightning in India in 2014 according to the National Crime Records Bureau, the most recent figures available.