Dorothy Hosein, interim chief executive of the East of England Ambulance Service NHS Trust (EEAST), wrote to staff on Thursday to share her thoughts "in light of recent difficult events".EEAST has faced severe criticism from staff over pressured working conditions following the sudden deaths, which happened between November 11 and 21. One anonymous staff member told our sister newspaper, the Eastern Daily Press, they believed crews were working "beyond breaking point" and EEAST was "sitting on a ticking time bomb". Ms Hosein said staff had raised a number of serious concerns and the trust had immediately commissioned an independent investigation. "We cannot comment further on that investigation, until it is completed, bearing in mind our commitment to protect the confidentiality of all staff," she added. "I want to assure you that we take any allegations of harassment and bullying very seriously indeed. "The trust has policies and practices in place to encourage staff to come forward, air their concerns and work with us, to resolve any conflicts and put in place the kind of support that they might need. "Your wellbeing is a key priority for us and top of our agenda." She added: "I would also like to thank you for the wonderful support, I hear about daily, that you give to each other in times of need. "I know that you are all very proud of the outstanding care that you deliver and it's a privilege to be part of this family." Ms Hosein also said she and executive colleagues wanted to develop an environment of "openness and transparency", which she said was "essential for a healthy happy organisation". "Our ambition is for all of you to feel able to raise concerns confidently and that these concerns will be acted upon without any fear," she added. But the message has failed to convince some EEAST staff who commented on her post on the trust's message board. One said: "Your engagements have amounted to nothing. "The past few weeks have seen us treated horrendously, and since the terrible news of our friends and colleagues it seems the pressure has been increased." The comments were later removed from EEAST's website. EEAST said it listened to staff concerns and "learn from and share our experiences". The trust added it would keep NHS England NHS Improvement up to date with the progress of the independent investigation. The BBC has reported it will be led by led by Martin Tiplady, a former human resources director at the Metropolitan Police. Mr Tiplady was made an OBE in 2010 for services to HR in the police. The three staff who died have been named as Luke Wright, 24, from Norwich, Christopher Gill, 41, and Richard Grimes.