Miranda Harris, a co-founder, died alongside the International CEO Chris Naylor and his wife Susanna on Monday.
Peter Harris is still alive and receiving treatment in hospital.
A Rocha's director of conservation, Andy Lester told Premier's News Hour the organisation and its partners are still coming to terms with the news:
"When it's really sudden and unexpected like this, it's a tragic loss for very, very many people around the world. There are people from Chile through to Peru, New Zealand and across the UK and the states who are reeling this afternoon.
"It's still very raw and it's very recent, so many people are grieving today and will be for some considerable time."
He went on to pay tribute to his friends saying: "When I was 16 years old, I first visited the A Rocha field study centre in Portugal as a completely directionless teenager and it was thanks to Peter and Miranda that I am speaking to you today because they brought in a deep passion for conservation for the natural world and for tying it together with the evangelical faith that gave me a sense of direction and purpose in life as a teenager and has enabled me to continue that work through what I'm doing and I know I'm not alone.
"I know there are many people out there who both found a passion for the planet but also a Christian faith through the two of them as leaders.
Lester praised them for their service to A Rocha and their environmental influence saying: "The legacy they leave is an incredible one."
He added: "These last few years have been eye opening for the churches globally, Christians around the world need to take a passionate interest in what is happening to our planet, whether it's climate change or species loss. So there's no end now to the extraordinary commitments by churches, entire denominations and communities, faith communities, around the world taking this message forward.
"Without Peter and Miranda's hard work at the beginning, and indeed, Chris and Susanna in the leadership of A Rocha International, we would not be seeing the extraordinary levels of growth that we're seeing now globally."
Lester urged the Christian community to stand with them at this difficult time and pray that Peter would "make a full recovery and begin to come to terms with what is a shocking loss for him personally, as well as for the wider A Rocha family."
"Pray for the children of both families that they can find comfort at this time and for the wider Christian community who today are suffering from a triple loss of some of the most extraordinary evangelical Christian leaders Britain seen in generations dealing with areas of environment and sustainability," he added.
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