Tributes have been paid after leaders of the Christian environmental charity A Rocha International were killed in a horrific car accident on Monday. 

Miranda Harris, co-founder of A Rocha, and Chris Naylor, CEO of A Rocha International, were both killed in the accident in Port Elizabeth, South Africa. 

Naylor's wife Susanna was also killed when the car they were travelling in collided with another vehicle.  Harris's husband Peter survived and is being treated in a local hospital where his condition is stable. 

A Rocha said in a statement that it was awaiting further news on his progress. 

"Above all, their families and friends are held in our prayers," it said.  "We know that this comes as a profound shock to everyone in the A Rocha Family and others all around the world. A more detailed announcement will be made in due course." 

Christian development agency Tearfund said in a statement: "Our thoughts and prayers are with A Rocha, and the friends and family who have been affected by this tragic loss." 

Ruth Valerio, Churches and Theology Director at A Rocha and a prominent environmental campaigner, tweeted: "Words simply can't express..."  

Other Christians expressed their shock over the loss. 

David Taylor, Assistant Professor of Theology and Culture at Fuller Seminary, said on Twitter: "Just gutted to hear the news of the sudden death of senior leaders in the Christian conservation organization A Rocha."

Ken McAllister, who works for Regent College, said: "I've know Peter and Miranda for nearly 20 years. When I heard of the accident today in our@regentcollege chapel service I was stunned.

"Miranda was such a beautify [sic] person, and we have many connections with A Rocha. We are deeply, deeply grieving this loss."