Video from the Chinese port-city of Zhoushan neighbouring Shanghai shows the sky turned blood-red under thick layers of fog.

Panic could be heard in the voices of the residents as they recorded the discoloured horizon, stirring apocalyptic fears.

The crimson sky was most prominent by the port, prompting worries that a fire had got out of control.

The red sky became a top trending topics on China’s Twitter-like social media, Sina Weibo, attracting more than 150 million views.

On Douyin, China’s version of TikTok, users called the red sky a bad omen over China’s handling of the Covid-19 pandemic, resurgent in neighbouring Shanghai.

One user said it means: ‘Accidents will happen’, with another adding. ‘I started to stock up on supplies.’

Researchers told Live Science that geomagnetic storms, caused by solar eruptions hitting the earth’s magnetosphere, might have caused the event.