A Northern Ireland man has been killed in Helmand province in Afghanistan.
Ken McGonigle from County Tyrone was working as a police mentor when he was shot by an escaped prisoner in the Musa Qala district on Saturday.
Two US marines are also believed to have been killed in the incident along with the gunman.
Mr McGonigle, a father of four originally from the Trillick area, had been working for the New Century civilian security firm.
In a statement, his family said: "Our dear husband, father and friend tragically lost his life whilst courageously helping the people of Afghanistan.
"Ken's primary motivation in life was his family; he was devoted to us all, as we were to him.
"He had the heart of a lion and died a hero."
New Century said it was a "tragic, but isolated incident" and said its thoughts and prayers went out to Mr McGonigle's family.
"His presence and contribution will be sorely missed by everyone in the company and at the NATO training mission," it said.
"Ken was a highly professional, deeply competent, well-admired and thoroughly committed colleague who made a material difference through his work."
New Century's chief executive is former Royal Irish Regiment colonel Tim Collins, while the retired detective chief superintendent Norman Baxter, a 30-year veteran of the RUC and PSNI, is also on the management team.
Mr McGonigle, a former police officer who lived in Magheramason, County Londonderry, and the local Presbyterian minister Rev David Hillen said members of his congregation had told him about the killing.
"They came to me after the service yesterday and told me the sad news and tears were shed - they were very upset indeed," he said.
"I called yesterday - it was a very brief visit - with his wife Gail and spoke to a few of the children just to tell them that many people in the church and community were thinking about them."
Omagh Councillor Bert Wilson, who knows Mr McGonigle's family, said they had been devastated by his death.
"We have quite a lot of retired police force and security force men from Northern Ireland out there and they are all in the same danger - it's tragic," Mr Wilson said.
Meanwhile, the Northern Irish fiance of an English doctor shot dead along with nine colleagues on an aid mission in Afghanistan has described her as an "extraordinary person".
Dr Karen Woo was working with a Christian charity providing healthcare in remote villages in the north-east of Afghanistan.
Her body was found on Friday in Badakhshan along with those of six Americans, a German and two Afghan interpreters who worked with her.
He fiance, Mark 'Paddy' Smith from Newtownards, said: "If you look at her life she was an incredible human being. You don't find too many people like Karen Woo in this world
"It is such a loss to the people of Afghanistan that someone that cared so much has gone.
"There are so many different things I will miss about her. Her love for life.
"Anyone who met her couldn't help but smile. She made people happy. She helped people wherever she could. She made time for people.
"If people needed assistance she would always be there. She could never say no, sometimes to the detriment of what she was doing."
Dr Woo's body is expected to be returned to the UK on Tuesday.