It was her two cousins who were the visionaries with her. Their deaths were predicted before hand.
From Wiki:
In 1936 and again in 1941, Sister Lúcia claimed that the Virgin Mary had predicted the deaths of two of the children during the second apparition on June 13, 1917. Besides Lúcia’s account, the testimony of Olímpia Marto (mother of the two younger children) and several others state that her children did not keep this information secret and ecstatically predicted their own deaths many times to her and to curious pilgrims.[23] In fact, it was the first thing Jacinta told her mother when she spoke to her after the initial apparition.[24] According to the 1941 account, on 13 June, Lúcia asked the Virgin if the three children would go to heaven when they died. She said that she heard Mary reply, “Yes, I shall take Francisco and Jacinta soon, but you will remain a little longer, since Jesus wishes you to make me known and loved on earth. He wishes also for you to establish devotion in the world to my Immaculate Heart.”[25]
If you are not asking about the other visionaries. I’m sorry I didn’t look that up.