A man in his 40s remains in custody in County Roscommon after the killing of Detective Garda Colm Horkan.

The 49-year-old was shot dead with his own gun in Castlerea Co. Roscommon late on Wednesday night.

Hundreds of people gathered in the pouring rain to attend a vigil for him in the town last night.

This woman says she felt it was important to show support to the local Garda Community.

The vigil for Detective Garda Colm Horkan in Castlerea, 18-06-2020. Image: Kacey O’Riordan/Newstalk

“I felt it was very important to come out because we depend so much on the gardaí in our town,” she said.

“We have a small town but we have a good relationship with the gardai and we feel safe when we know they are around.

“I think it is very important now more than ever that the public support the gardaí. It is tough out there and I think they are doing a good job.”

Detective Garda Colm Horkan, who was shot dead in Castlerea last night. Image: An Garda Síochána

Gardaí believe Detective Horkan’s gun was taken from him after he became involved an altercation while he was on patrol on Main Street in the town.

The Garda Commissioner Drew Harris described the killing as a “random act.”

A separate memorial event was also held Detective Horkan’s colleagues.

The 49-year-old was originally from Charlestown in County Mayo and spent 24 years as a member of An Garda Síochána.

He is survived by his father, sister and four brothers.

Books of condolence have been opened for him in Garda Stations all around the country.

Meanwhile Dublin City Council has opened an online book of condolence, with all messages to be presented to Detective Horkan’s family.