Some were shot. Armed guards stood over the masses and coerced them to comply. Mothers forced their crying children to comply.
The Commie loyalists of the Peoples Temple even killed people stateside after the Jonestown massacre.
Ah - that part I knew (except maybe for hunting the people down afterwards) although my understanding is that a great many did it voluntarily.
One thing Im fuzzy on is why he did it. I believe he was being investigated but if he was a socialist operative youd think hed send his people to war first before ritual suicide.