You may be interested in the Massacre of Amritsar of April 1919 when British troops opened fire on a group of unarmed Indians killing hundreds and wounding hundreds more. That region is a Sikh region. The crowd of around 10,000 was made of of men, women and children and some were there to celebrate their spring festival of Baisakhi and some were organising to protest recent extensions of repressive laws on Indian life.

The British troops under Brigadier General Reginald Edward Harry Dyer arrived and sealed off the only exit of the walled space that the people were gathered in and then opened fire on the crowd. It was described by Indians as the British soldiers shooting until they ran out of ammunition.

It left huge scars on Indian and British relations. The Indian poet Tagore, noble prize winner for literature, turned in his knighthood.

You can reference this in A History of Modern India edited by Claude Markovits.