When teachers at The Study Preparatory School set out trestle tables with soft drinks and cakes in the sunshine on Thursday morning, their only concern was rewarding Year Three pupils with a fun and fitting end to their studies.

Many parents had chosen to attend the event at the exclusive school near Wimbledon Common, south-west London.

The narrow road outside the independent prep school was lined with parked cars, including Porsches, Range Rovers and Maseratis.

There is no doubt the children, aged between seven and eight years old, would have been tremendously excited about the day, which marked the start of their long summer holidays.

But shortly before 10am, a tragedy as unfathomable as it was violent shattered the peace of that preparatory school’s celebration.

A black and gold Land Rover careered off the road crashing through a fence and colliding with children and parents before thudding to a halt against the red brick wall, sending shards of glass flying.

One man is said to have run from the building declaring that a child was dead before pleading for the road to be cleared for ambulances.

There were initial fears that the incident could be a terrorist attack.

As 999 calls relayed the severity of the crash to emergency services, scores of police, ambulances and fire brigade vehicles hurtled towards the scene in the suburb which is currently hosting the Wimbledon tennis championships.

Exactly what happened in the lead-up to the catastrophic collision remains unknown.

Initial reports suggested the driver, a woman in her 40s possibly returning from the nearby Royal Wimbledon Golf Club, had suffered a “seizure” or perhaps a “heart attack”.

However, police later said the woman had been taken into custody and was being questioned on suspicion of causing death by dangerous driving.

The emergency response to the crash was rapid; scores of paramedics arrived to treat 16 patients at the scene. It soon emerged an eight-year-old school pupil was among the dead.

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A total of 10 further patients, it is not known how many were children or adults, were ferried to hospital. Some suffered injuries so severe only an air ambulance could take them there.

A number of those injured were said to be in a critical condition.

In the mayhem that followed the incident, parents dashed to the Camp Road school in a desperate effort to try to check their children were not among the injured.

As a police cordon was set up, parents were seen hugging their children as they ushered them underneath the blue and white tape into cars along the streets buttressing the golf club and common.

Some children were seen undergoing treatment for cuts and bruises in the scores of ambulances parked up around Wimbledon Common.

But a hint of the horror that those police, paramedics and firefighters saw when they arrived first at the school was summed up when Detective Chief Superintendent Clair Kelland told a press conference at the scene that a child was among the dead.

Despite being an experienced senior police officer, even she lost her composure.

For just a few moments, the policing commander for south-west London, who is a mother herself, struggled with the word “eight years old”.

“Very sadly one of the children, an eight-year-old girl, died at the scene,” she said, clearly considering the magnitude of that child’s parents’ loss.

“Our thoughts are with her family at this incredibly difficult time.”

A few feet away, the chairman of the board of governors, John Tucker, said that the local community was “profoundly affected” by the “tragedy”.

He declined to comment further as he stood beside the school’s headteacher Helen Lowe, who was holding hands with headteacher-elect Sharon Maher.

As the injury toll was read out by the emergency service officials, they gripped one another tighter and tighter.

Throughout the press conference, a television helicopter filmed above. Its aerial photographs captured the aftermath of the crash.

A large mat was spread out on the ground where the tea party was believed to have been held.

Nearby was a table with a white cloth on it with drinks. A fire extinguisher was lying near the 4×4 car, its bonnet crumpled against the wall of the school.

Much of the confusion for parents was just how a Land Rover could have been able to smash into the school when the speed limit was just 20mph.

Some local residents, who did not want to be named, said it was normal for some parents of children at the prep school to attend the end-of-term tea party, raising the prospect that they had brought younger children not yet of school age to the event.

There were fears that some of those injured could be even younger than those in Year 3.

Although police urged people not to speculate about what actually happened, in Wimbledon Village, where shops were adorned with fluorescent green tennis balls to mark the grass tennis tournament, the tragedy was very near to their thoughts.

Even the tournament organisers issued a statement on Twitter:

Stephen Hammond, the MP for Wimbledon whose daughter previously attended the school, said he understood that several of those hurt were “critically injured”.

He said: “Given the scale of the response from emergency services… this is a very serious incident.”

A statement on the prep school website said: “We are profoundly shocked by the tragic accident this morning at Wilberforce House and devastated that it has claimed the life of one of our young pupils as well as injuring several others.

“Our thoughts are with the bereaved family and with the families of those injured at this terrible time.

“It is still far too soon to fully understand what happened, but we are well aware of the significant impact this dreadful event will have on our pupils and their families.

“Their welfare remains our top priority and we will be doing everything we can to support them, especially those who suffered injuries.

“Now that a police investigation is under way we will not be making any further public statement for the time being and would ask that the privacy of our school community is respected at this deeply upsetting time.”

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