A civic service led by the Bishop of Plymouth will be held at the Minster Church of St Andrew on Wednesday.
The service taken by Right Reverend Nick McKinnel is one of a number of tributes announced by Plymouth Council following Thursday's tragedy in which five people were killed, including a three-year-old girl and the gunman's mother.
A minute's silence will be held in the city on Monday at 11a.m.
On Friday, a range of denominations provided support following the tragedy, including the Plymouth and Devonport Methodist Circuit.
The Roman Catholic Bishop of Plymouth, Right Reverend Mark O'Toole, asked churches in Keyham and the wider area to remain open to provide sanctuary for the local community.
The Vice-President of the Methodist Conference, Barbara Easton, announced on Facebook that she would visit Plymouth on Sunday.
"The community of Plymouth is much in our thoughts and prayers. Throughout the day, colleagues from the local Methodist circuit have been out providing support to people in the area local to the shootings. This is such a tragic and uncommon event that the whole city has been very much shaken by what has happened. I will be going to church in Plymouth on Sunday and will take with me the love, prayers and good wishes of the wider Methodist family."
Devon and Cornwall Police are being investigated over the decision to give Plymouth gunman Jake Davison his weapon back - despite seizing it last year.
His weapon had been seized after he was accused of assault
Books of condolence are available for the public to sign at several locations and with varying opening times. These are St Mark's Church in Sanctuary Close, Ford, from 9am to 5pm; St Thomas Church in Royal Navy Road, Keyham from 9am to 11am on Sunday; The Council House, Armada Way from 9am to 5pm on Saturday and 10am to 4pm on Sunday and Ford Primary School, Cambridge Road from 9am until 5pm.
There is also an online book of condolence on the council's website.