Sources in the Catalan police, the Mossos d’Esquadra, said the incident took place on Tuesday evening at their home in Sallent, some 60 kilometres (35 miles) north of Barcelona.

The pair had reportedly left hand-written notes next to the balcony but the police have so far been very cautious in their use of language.

While police have ruled out any criminal cause, they have said the pair “plunged” off a third-floor balcony. One twin died at the scene while the other was rushed to hospital in critical condition, they said.

The incident has shaken Spain, prompting fierce speculation about the state of mind of the two girls who had reportedly been bullied at school.

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But Education Minister Pilar Alegría urged people not to jump to conclusions while the investigation was still under way.

“Particularly since the pandemic, we’ve known there has been an increase in self-harming behaviour among young people, particularly adolescents.”

“We are working with all the relevant authorities because even if it’s just one case (of bullying).. we need to try and find the best solution,” she added.

The tragedy has shaken this area of 7,000 residents which declared three days of mourning and suspended its carnival.

La Vanguardia newspaper said the girls were from an Argentine family which had moved into the area some two years ago.

A close family friend told the paper the girls had suffered taunts and insults at school.

Recently, the mockery had increased after one of the girls said she felt like a boy and had wanted to be given a boy’s name, El País newspaper reported.

But sources in Catalonia’s regional education department said “the school had not picked up on any specific problem of bullying” although it had “provided psychological support and counselling to the girls since the start of the school year”.

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