At least 26 people were killed when thunderstorms and lightning struck parts of India's northern state of Uttar Pradesh on Saturday, dpa quoted news reports as saying. The IANS news agency, quoting official sources, reported that 16 people had died in the central Shahjahanpur district, 190 kilometres north of state capital Lucknow. Most of the deaths were caused by houses collapsing or trees and electrical poles falling down on locals or their dwellings. Thunderstorms claimed six lives in Lakhimpur-Kheri, while four people were struck by lightning in the Ambedkar Nagar district. The storms are typical of the pre-monsoon period and are generally caused by cyclonic pressures formed over the northern regions of the country. Fifty-six people were killed in similar storms in Uttar Pradesh and neighbouring Bihar states on Wednesday. India's monsoon season usually lasts from June to October.