Police investigating how a massive inflatable sculpture tore free from its moorings, killing two people and injuring more than a dozen others, said today that were keeping an open mind on the incident and had not ruled out the possibility of sabotage.

A 38-year-old mother and a 68-year-old grandmother were killed and more than a dozen people were injured on Sunday afternoon when the walk-in sculpture - the size of 25 Olympic swimming pools - rose skywards from a park in County Durham. The artwork lifted about 30ft into the air before colliding with a pole supporting a CCTV camera.

Claire Furmedge, 38, was in the huge maze with her two daughters, aged 6 and 8, and Elizabeth Anne Collings, 68, was inside with her 14-year-old grandson when it left the ground during a sudden gust of wind.

They were among an estimated 30 children and adults, including the artist who created the Dreamspace installation, who were trapped as it rose above Chester le Street’s Riverside Park.

Thirteen people were injured in the incident, including a 3-year old girl who was in a serious condition in Newcastle General Hospital today after suffering crush injuries.

As rumours circulated that one of the mooring ropes had been loosened shortly before the structure left the ground, Chief Superintendent Trevor Watson said today: "It is very early in the investigation and too early to speculate.

"We are keeping an open mind and there’s no information we have received that may have been the cause. We are bringing a search team back on site today and are keeping a very open mind to the cause of the accident and will be investigating every aspect.

"It’s difficult to say how long this investigation will take but we’ll take it as far as we need to.

"Certainly I'm not suggesting that we have specific informaton that it was tampered with, but we're not ruling anything out," he added.

It was thought that there were up to 30 people in the inflatable at the time it tore free, although Mr Watson said it was still unclear whether the two women who were killed had been inside it.

There were hundreds of others on the ground who witnessed the incident, including Maurice Agis, the artist responsible for Dreamspace, who has built and toured with various versions of the inflatable since 1996. Mr Agis has been interviewed at Chester-le-Street police station.

A friend of the artist said today: "He’s very distressed. We were all there, he was there. He’s given ten years of happiness to people and then this happens - he’s very sad."

The sculpture covered around 2,500 square metres and consisted of inflated rooms made of translucent coloured PVC connected by tunnels. Visitors removed their shoes and were asked to don coloured capes so that they became part of the artwork itself.

One witness, Mark Spooner, told the BBC today that he heard three "snaps" as the ties holding the structure broke.

"As you heard them snap the wind just got underneath the belly of it and it lifted right up. It flicked right over. We thought it was going to come over and land on us, " he said.

"At the time you’re just thinking, ‘There are people inside that’. It must have blown 20 or 30 metres across the park and then it caught a pole and a lot of trees.

"About 40 men came from out of the park and they ran over and we all just started ripping it up with our hands. I remember sticking my head through and shouting, ‘Get out, get out.’ If it had gone any more it would have been down into the river."

The remains of the 15ft-high structure, which had appeared at venues across the world, were still strewn around a wide area of the park that was cordoned off by police and Health and Safety Executive officers today.

Among those at the park today was Chloe Wilson, 7, who witnessed the tragedy and returned to lay a bunch of flowers at the spot where she saw the elder victim die.

Chloe, who was in the park with her aunt Catherine yesterday afternoon, today told how dozens of people tore at the inflatable as people inside screamed in terror.

She said: ""I was in the park with my aunt when it started to go up in the air. There was loads of people running about and we tried to run towards it after it came down on the ground.

"Lots of people were trying to rip it open with their hands and little knives and I was asking if I could help. It was very scary and people were screaming. I saw a lady clinging on and then falling out and she was lying on the ground with people around her. I think she died.

"I really wanted to come here today and put some flowers down."

Her mother added: "She had a terrible night through this. She did not sleep very well and we thought it might help for her to come back today in the quiet. It was terrible what happened and you would never expect anything like it."

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