Five men have died in what police are describing as an industrial accident in Birmingham.
West Midlands Fire Service said a large concrete structure containing metal had collapsed at the site.
Two ambulances, an air ambulance, a hazardous area response team and an emergency planning officer were sent to the scene.
An Ambulance Service spokesman said: "On arrival, ambulance crews found a wall that had collapsed.
"Sadly, there was nothing that could be done to save the five men who had been working next to it.
"A sixth man was partially trapped by the falling concrete but had managed to get out from the rubble himself.
"He was treated at the scene by ambulance staff and the doctor from the air ambulance for a broken leg before he was taken to Heartlands Hospital for further treatment."
Emergency crews were called to Hawkeswood Metal in Aston Church Road at 8.45am.
An investigation is under way and the Health and Safety Executive (HSE) has been notified.
Detective Superintendent Mark Payne said: "We are still in the very early stages of this investigation to determine exactly what happened this morning.
"Sadly five people have lost their lives and we have several teams of specialist officers supporting their families at this time.
"This has been a very traumatic incident for those who were at the site this morning and we will continue to work alongside the HSE and the other emergency services at the scene."
Thr Fire Service deployed its Technical Rescue Unit (TRU) to the scene equipped with heavy lifting and cutting equipment.
Assistant Chief Fire Officer Gary Taylor said: "This is a devastating incident for everyone involved. Our thoughts and deepest sympathies are with the victims' families and colleagues.
"Once the police have finished their initial examination of the scene, our absolute priority will be to ensure that the bodies of those who have lost their lives are recovered in the most timely and safe way possible, and with the utmost dignity and respect."
Mr Taylor described the scene as extremely challenging, with a significant tonnage of concrete and metal, and a structure that is still unstable.
"We have an assertive recovery plan in place and expect this operation to take several hours," he said.