BBC reports that the revered nun, born in 1910 and died in 1997, has been proclaimed as a saint by Pope Francis, today (September 4, 2016).

Thousands of pilgrims were at the St Peter's Square in Vatican city, Rome for the Mass and canonisation of the reverend sister.

Before she was declared as a saint, Cardinal Angelo Amato read a brief biography of her work.

Afterwards, the Pope went on to canonise her in the name of the Church.

"After due deliberation and frequent prayer for divine assistance, and having sought the counsel of many of our brother bishops, we declare and define Blessed Teresa of Calcutta to be a saint and we enrol her among the saints, decreeing that she is to be venerated as such by the whole Church", he said.

Onlookers included Missionaries of Charity sisters, 13 heads of state or government, 1,500 homeless people, who were served pizza lunch by 250 nuns and priests of the Sisters of Charity order.

Speaking on the huge honour, Charlotte Samba from Gabon, said: "Her heart, she gave it to the world. Mercy, forgiveness, good works. It is the heart of a mother for the poor."

She was supported by a senior sister at Mother House in Kolkata (Calcutta), Mary Lysa, who said: "It's a day of rejoicing, a day of gratitude and a day of many, many blessings."

Mother Theresa, now St. Theresa, was known for her work with the poor, miraculous cures of the sick, and amazing love for God.