The explosion happened at a service station in the village on Friday afternoon.
The close-knit community of about 400 people is coming to terms with an unprecedented scale of loss.
Candlelit vigils are being held in Guildhall Square in Derry as well as cross Donegal.
At a vigil in Letterkenny, photographs of the victims were placed in Market Square and people were urged to talk about what happened.
The vigil was organised by the Letterkenny Community Development Project as a show of support to the families of those killed or injured.
Project director Gerry McMonagle said people needed to talk after the tragedy to process what had happened.
“This was an awful incident. I think the randomness of it, it could have happened to any one of us, and that brought it home to people,” he said.
“In this crowd tonight, everyone will know someone who was affected by this, it is such a tight knit community, when one hurts we all hurt.
“That’s why we’re all here tonight in solidarity and sympathy with those families.”
In Derry, 10 red candles were lit on the steps of the Guildhall, as Mayor Sandra Duffy paid tribute to the victims.
An investigation is under way into the cause of the explosion, but police have said it appears to have been a tragic accident.
Tributes to those affected have been paid by the Pope, Irish president and neighbours.
On Monday, a statement from King Charles and the Queen Consort said they expressed their “most heartfelt sympathy and deepest condolences” to people who had lost loves ones and with “the people of Ireland”.
The monarch said they had experienced the “strong sense of community” that exists in Donegal from their visit to the county in 2016.
The first funerals of two of the victims, Jessica Gallagher, 24, from Creeslough, and Martin McGill, 49, who was originally from Scotland, will take place on Tuesday.
Miss Gallagher’s aunt Dolores Gallagher said her niece was a “beautiful woman”.
The 24-year-old had recently graduated from IFA [International Fashion Academy] Paris and was due to start her first fashion and design job in Belfast on Monday, Ms Gallagher told BBC Radio Foyle.
“She was lively, vibrant, and lit up every room she walked into.
“She was such a happy person and a hard worker – she wanted her life to make a difference in the field of fashion and art. She was so proud to belong to Creeslough.”
The funeral of James O’Flaherty, from Sydney, Australia, will be held on Wednesday morning, followed by the funerals of Catherine O’Donnell and her son James Monaghan, from Creeslough, on Wednesday afternoon.
Tags: