Hundreds turned out for a candlelit vigil in Dunleer in Louth on Monday as the local community, family and friends joined in solidarity for Cameron Reilly.
Cameron had been studying hospitality at Dundalk Institute of Technology and a number of staff and students arrived to pay their respects.
He had just finished his first year in the college.
One of the young man’s lecturers, Mairead McKenna, said “we’re absolutely torn up” by his death.
“He was a very quiet young chap, well behaved,” she said.
Another lecturer, Michael McNamara said many of the students met at the college earlier today.
Mr McNamara said he lives in Achill and didn’t know it was Cameron until yesterday.
“I knew someone had died, I didn’t know who it was. Only when I came up today, I was just totally devastated,” he said.
“It was only when I seen his picture, we’d be a small group.
“I’m gutted, absolutely gutted, just wondering what kind of society we’re living in now,” he added.
The tiny church in the small Louth town was packed inside - with hundreds holding candles aloft for the 45 minute service - while hundreds more stood outside in silence.
One student from DKIT stood up to say a poem for her pal, entitled “He is gone”.
“You can shed tears because he is gone or you can smile because he has lived,” it read.
Asked how students were holding up following the news, Mr McNamara said:
“His classmates were there today, we had tea and coffee and they were gutted,” he said.
Priest Michael Murtagh said this was an opportunity to pray for Cameron and show solidarity with his family.
He added that it was also to “take a stand for all that’s decent and good in the world”.
Gardaí are investigating if a young person known to Cameron Reilly murdered the teenager in front of a number of youths.
The body of the 18-year-old was found in a field near Dunleer, Co Louth, at around 8.30am on Saturday.
The teenager had been socialising with up to 20 young males and females in the field near the Rivervale area in the hours before his murder.
A senior source last night said gardaí were appealing for the people who were with Cameron before his murder to come forward.
"At this stage, it appears that a row occurred which led to his death, but the motive has not yet been established.
"Gardaí believe a number of people may have been present when Cameron was murdered, and would urge them to come forward," the source told Independent.ie.
Gardaí are investigating if he was killed by a person known to him, and if a number of young people may have been present when the killing occurred.
No arrests have yet been made, but gardaí have spoken to a number of Cameron's friends to gather information on his movements prior to his killing.
A missing mobile phone, which belonged to Cameron, is also being searched for and may prove crucial to the investigation.