Air ambulances are unable to land at a hospital in Cambridge after a US military aircraft damaged its helipad during a training exercise.
The US Air Force CV22 Osprey tiltrotor stripped the matting of the helipad from the ground as it took off from Addenbrooke's Hospital on Wednesday.
Video posted online shows military personnel leaving the aircraft before it takes off and debris is sent flying.
It means that critically ill patients are currently unable to be airlifted to the site, which serves as the East of England's major trauma centre for three air ambulance crews.
They are instead being flown to Cambridge City Airport and making the large leg of their journey by ambulance.
Repair work is under way, with the East Anglian, Magpas and Essex and Herts Air Ambulance services confident it will be back in use soon.
Maj Keavy Rake, of the USAF's 48th Fighter Wing, said: "The area was surveyed according to our policies and procedures and some damage did occur.
"We are taking steps to rectify as soon as possible. We are greatly appreciative of the relationship and coordination we have with the UK."
Several of the tiltrotors, which operate like helicopters, are based nearby at RAF Mildenhall in Suffolk.
A spokesperson for the ambulance services said: "Due to an incident at the Cambridge University Hospitals helipad involving a military aircraft on Wednesday April 21 the helipad is temporarily unavailable to air ambulances.
"The next closest helipad is at Cambridge City Airport, where one of the East Anglian Air Ambulance (EAAA) teams is based.
"It will be possible for the EAAA helipad to be used as an alternative landing site during this time and have patients transferred to Addenbrooke's from there by land ambulance, with critical care staff on board."
A spokesperson for Cambridge University Hospitals NHS Trust added that they were still treating patients "as normal".