Simplify the following text for a Grade 10 native English-speaking person.
Original: It was by his command that 90 troops , including 25 Gurkhas of 1st\/9th Gurkha Rifles , 25 Pathans and Baluch of 54th Sikhs and 59th Sindh Rifles , all armed with .303 Lee-Enfield rifles ( and the Gurkhas additionally armed with khukris ) opened fire on a gathering of unarmed civilians , including women and children , gathered at the Jallianwalla Bagh in what came to be known later as the Amritsar massacre .
Simplified: It was under his command that 90 troops , made up of 25 Gurkhas , 25 Pathans and Baluch , all armed with .303 Lee-Enfield rifles and the Gurkhas who were also armed with khukris opened fire on a gathering of unarmed civilians , including women and children gathered at the Jallianwalla Bagh in what came to be later known as the Jallianwala Bagh massacre .