A 23-year-old Chinese woman has allegedly died from an electric shock when using Apple’s iPhone 5 while it was being charged, her family members claim, according to media reports.

The older sister of alleged victim Ma Ailun took to Sina Weibo, China’s popular Twitter-like social network, over the weekend to demand an explanation from Apple and urged people not to use their phones while charging them.

A Sina Tech report said that Apple has issued a statement expressing condolences to Ma’s family over the unfortunate incident, and vowed to investigate the incident thoroughly. The company also said it would cooperate with authorities over the matter.

Another report, this time from China Daily, said that local police confirmed Ma had died of electrocution, but have not concluded whether her phone played a part in causing the incident.

Experts have noted that there is a risk in using any electrical device while it is being charged, according to a South China Morning Post report — be it a shaver or a phone. An expert in the report also cautioned that the exact circumstances of the incident are not clear, and it would not be suitable to jump to any conclusions at this stage.

China is known for selling Apple products on the grey market, with the iPhone 5 landing in the country less than a week after Apple began selling it last year, and counterfeit iPhone 5 models had arrived by then too.

Ma’s sister mentioned on Weibo that the phone was bought last December and still under warranty, and the family has handed the phone over to authorities for investigation.

Reports have said that Ma, a resident in the northwestern Chinese province of Xinjiang, had been a flight attendant at China Southern Airlines, though she recently quit her job. Ma’s sister on Weibo mentioned that she had been due to get married on August 18.

We have reached out to Apple for comment and will update with any further details provided.

Image Credit: Jean-Sebastien Evrard via AFP/Getty Images

Read next: Apple reportedly inks deal with Samsung to provide iPhone chips from 2015