The head of Catholics in England and Wales has spoken of his "utter shock and sadness" at the killing of a teacher stabbed to death in her classroom at Corpus Christi Catholic college in Leeds yesterday.
Ann Maguire, who was due to retire at the end of this term and who had just celebrated her 40th year in teaching, was attacked in front of students.
In a statement, Cardinal Vincent Nichols, said: "My heart goes out to her husband and daughters, to their wider family, to everyone at Corpus Christi Catholic College and to the parishes connected to the College.
"I want to assure them of my prayers, and those of the entire Diocese of Westminster at this time. May the Lord comfort the bereaved, consoling them with his unshakable promise of eternal life.
"I pray, too, that through the shock, distress and anger that this action evokes, the light of Christ may shine, a light that calls us to trust in his merciful love, that brings us a touch of calm and healing and that opens our hearts to each other in our bewilderment and dismay."
Prayers have been said at a mass for the 61 year-old teacher. Some of her former pupils attended the service at Corpus Christi Catholic Church, which is connected to the school.
Many were in tears as the congregation was led in prayers by Monsignor Paul Fisher.
Monsignor Fisher said: "Yesterday evening, the community gathered here in church as well as outside to light candles and to say a prayer.
"By the time the church was closed, the candelabras were full of light.
"Today we pray for the light of hope. Hope for ourselves that we will come to terms, eventually, with what has happened.
"We pray for all those young people at our school next door and their teachers. We pray for Ann's family and friends."
A 15-year-old boy remains in custody at a police station in the city.
The school has remained open and nuns based at the Catholic Church opposite have been comforting pupils, parents and staff.
Upon hearing of the tragedy, Archbishop-elect Malcolm McMahon OP, Chairman of the Catholic Education Service, said: "I was shocked and saddened to hear of Ann Maguire's death yesterday.
"My prayers, and those of every Catholic parish and school in England and Wales, will be with her family and friends, the staff and students of Corpus Christi Catholic College in Leeds, and all who have been affected in any way by this senseless tragedy.
"Ann gave her life to the College and Catholic education, and thousands of young people have benefited from her kindness and hard work over many years. May she rest in peace."
Scores of bouquets have been left outside the school, where a constant stream of well-wishers continued to pay tribute.
The school's headteacher Steve Mort paid tribute to the Spanish and RE teacher: "Ann Maguire was a wonderful, caring individual.
"She was an outstanding teacher and an outstanding leader.
"She'd been a cornerstone of the school community for 40 years, she'd touched the hearts of three generations of pupils."
Mr Mort also did not think detectors were necessary, adding that the school was a "safe environment".
A 15 year-old boy was arrested yesterday.
Det Supt Simon Beldon form West Yorkshire Police spoke to reporters outside the gates of the school earlier today.
He said: "The suspect does remain in custody and will be interviewed at some point during today.
"Given his young age, this is a process which needs to be handled very sensitively and may take some time to complete.
"The pupils who witnessed this incident are still being interviewed by specialist officers and are very experienced in dealing with child witnesses and they will ensure their welfare is paramount."
The attack has caused debate around whether schools should have tighter security, including metal detectors to check for weapons.
Patrick Reagan formed Christian youth charity XLP, after being asked as a youth worker to help a school where there was a stabbing incident in the playground in 1996.
He told Premier's News Hour why he thinks education around knife crime is the only way forward.