BBC Reporter: Flames ravaging the church at the height of the fire. These pictures were filmed by a local resident. St Bernardís church had been a focal point for many people, with around two and a half thousand parishioners attending Mass there each weekend.
By daylight, little more than a charred shell of the church remained. Fire crews were at the scene from early morning, arriving shortly before four oíclock. Fire officers however were able to save the priestís vestments and altar vessels which had been kept in a safe.
We do, of course, plan to rebuild St Bernardís. A new St Bernardís will rise out of the ashes that we see here this morning and we will do that as quickly as possible. And I want to assure our people that that will be our priority and we will replace this special place for them. We will replace it as soon as possible.
BBC Reporter: A sniffer dog was used to help forensic experts examine the interior of the church to establish exactly how the fire began.
This is an area where there is good community relations, and there are a lot of people on the ground working to keep the two communities working together, and we would hope that that would continue. We are treating this as an arson at this stage and, once we get our forensic teams in, weíll be able to give a definitive answer as to what the cause of the fire was.
BBC Reporter: Morning mass, usually held in the church, instead took place in the assembly hall of the local primary school. Earlier, other parishioners spoke of their shock.
The whole area is devastated with whatís happened. I mean, as I say, just standing here looking at the church, thereís just an absolute nothing left at all. Everybodyís devastated. Thereís kids in the school this morning actually crying because of it, you know. The whole school used that church every day. One of the classes is always in it, and itís just, itís tragic.
The children donít know why they would set fire to a chapel, what the point of it is - very, very annoyed. Absolute disgrace.
BBC Reporter: As pupils continued to arrive at the school, Protestant churchmen offered their sympathy about the fire.
I think itís dreadful to find a church desecrated in this way, destroyed. I was down in Newmills Church, one of our own churches, last Thursday evening and I have some sense of the anguish that people go through when their place of worship is destroyed. Itís heart-rending to see a building gutted in this way.
The ruins of the church will be demolished after forensic tests are completed. Rebuilding it will be a far longer task.
Noreen Erskine, BBC News, Glengormley.