Watch: Sky over Chinese city turns blood red. Here's what happened

Citizens of China's port city of Zhoushan were in for a rude shock after the sky turned blood red on Monday evening.

The crimson sky triggered panic among citizens who recorded the phenomenon and shared it on social media. It also prompted concerns of a massive fire, according to some reports.

The nature of the phenomenon also prompted Twitter users to come up with their own theories. Some even called it an ‘apocalyptic’ sign while others called it an illusion caused by Marvel's Scarlet Witch.

The theories were, however, put to rest as authorities explained that refraction and scattering of light from those in the port caused the sky to appear red.

According to reports from the local Chinese media, the staff of the meteorological bureau said, "When weather conditions are good, more water in the atmosphere forms aerosols which refract and scatter the light of fishing boats and create the red sky seen by the public."