Police are treating a “significant” fire which completely destroyed Norwich flat as arson

Firefighters said it was 'very lucky' no-one was seriously injured or killed following a fire which ripped through the flat in Penn Grove, off Aylsham Road, in the early hours of Saturday, September 9.

Norfolk Fire and Rescue Service has not been able to determine the cause of the fire with their investigations proving 'inconclusive'.

The case has since been referred to police who are treating it as arson.

A spokesman said the investigation was ongoing but no arrests have yet been made.

There was no-one in the flat where the fire started but the alarm was raised after the smoke alarm in the property above went off.

Watch manager Steve Keen said: 'There could've been injuries or fatalities. It's very lucky no-one was hurt.'

There was no-one in the flat where the fire started but the alarm was raised after the smoke alarm in the property above went off.

The occupant of that flat then looked out to see the fire and called the brigade.

Station Manager John Baker, who was one of those who attended the blaze, said: 'A smoke alarm will always be the best way of alerting anyone, particularly people who are asleep, of a fire.

'It's very important to make sure they are tested and working all the time. They clearly save lives.'

A passer-by shouted up to say he had also called the emergency services after seeing the flames.

Appliances from Sprowston, Earlham and Carrow raced to the scene at just before 5.30am on Saturday, September 9.

At its height 17 firefighters were involved in putting the fire out.

Speaking at the time, Jake Marshall, 26, who lives on Penn Grove, said he woke up at 5.30am after hearing what he thought was people damaging cars.

He said: 'It turned out to be a fire and the whole front window was hanging off and fell down.

'Flames were coming out the front and back. There was a lot of smoke.

'I've never seen anything like it before - it was crazy.

'You always see things like that on TV and never expect it to happen across the road.'

A 76-year-old woman, who did not want to be named, said she heard a 'crackling' which she had also thought had been cars being broken into.

She said she looked out saw the smoke coming from the flat and dialled 999 but was told they were already on their way.

She said: 'I was looking out of the bedroom, thinking about the poor woman underneath and then the window just flew out - the complete frame just fell out.

'I thought 'Oh my goodness'.'

A 58-year-old woman, who also did not want to be named, said a crackling of glass woke her. She looked out saw the fire and 'people coming out of their flats shouting'.

She said she saw the flames coming out from the front then the back and thought 'Oh my God'.

Watch manager Steve Keen from Sprowston Fire Station said: 'On arrival we were met with flames coming out of several windows so it was a significant fire.

'We sent in the breathing apparatus team and extinguished the fire.'

Although it was not known initially whether anyone was in the flat it is now known to have been empty.

The fire service is now trying to contact the person who lives there and the property owner.

Mr Keen said people were evacuated from the flat above and the one below during the incident.

He said: 'There's always a danger of it spreading which is why we evacuated the flats above and below.'

The flat has been 'completely destroyed' in the incident which has also caused light smoke damage to the properties above and below.

They are now safe to go back into but it could have been much worse.

Mr Keen said: 'There could've been injuries or fatalities from that. It's very lucky no-one was hurt in that.'

Mr Keen said the incident emphasised the importance of having smoke alarms.

Witnesses to the fire should call Norwich CID on 101.