A Norfolk-based steelwork contractor is taking part in an investigation after a frame it built for a five-storey church collapsed.

DGT Structures from Lenwade, near Norwich, was hired to erect the frame for a new �6.1m City Gates Christian Centre in Ilford, east London.

On Tuesday the frame partially came down, but all 22 workers on the site escaped unharmed. It is believed the site team had clocked off for the day just minutes before the collapse.

David Drury, DGT's finance manager, said: 'We have nearly finished working on the site and I don't think any of our employees were there at the time. We are fortunate that nobody has been injured.

'We cannot comment too much because the Health and Safety Executive is investigating what happened, but our designer and erection manager have been at the site helping with the investigation.

'We have been instructed to tell people to go through the main contractor, Ashe Constructions' website, www.asheconstruction.co.uk, for the latest information.'

HSE investigators have still to determine what caused the steel frame structure to collapse, despite eyewitness speculation that steel beams spanning the building's main auditorium failed, bringing down surrounding steel work.

Ashe Construction's business development director Andrew Morris said: 'Work stopped at the site about 15 to 20 minutes before the collapse.

'Thankfully most of the guys had left the site. A few were left within the site set, up but no one was injured.It would be inappropriate to speculate on what caused the collapse.'

Eyewitnesses said it was a 'miracle' no-one was killed following the collapse of the building.

Mick Pandher told a local paper that he thought it was a 'thunder storm' when he looked at the building.

He said: 'Seconds later, I saw the whole building going to the floor.

'It was very sudden. It was like when you see a building being demolished. It came down in a straight line.'

A fire brigade spokesman said that six fire engines and four fire rescue units were sent to the incident, which happened at about 4.30pm.

A spokesman said: 'The steel frame surrounding it collapsed and scaffolding from the construction site also fell into a nearby car park, damaging six cars. All 22 construction workers on the site escaped uninjured.

'Crews used specially trained dogs to complete a systematic search of the area and were able to confirm that no-one else was involved in the incident, although one passer-by was treated for shock by London Ambulance Service.'

Work on the site started last June with construction due to last 16 months.

A man who told a local paper he worked on the site described it as a 'well run and organised site with a good safety record.'

david.bale2@archant.co.uk