A vast amount of a mud-like substance that suddenly began gushing out from the ground in the middle of the road baffled residents of a city in eastern China as it kept bubbling like hot magma and blocked traffic.

Concerned residents reported the bizarre occurrence on two different sections of the road in the city of Nanjing, in Jiangsu Province, on October 28.

Video footage shows an unknown reddish-brown liquid continuously emerging from beneath the ground and spilling out onto the street.

Stranger still, the mud-like substance kept bubbling as it gushed out in vast amounts. The flowing liquid reportedly occupied a large area of the road, forcing vehicles and pedestrians to change their routes.

Many locals were baffled as to what the runny material could be. Officials later said that they had received multiple reports from the public and sent out community workers to inspect the scene.

Police also arrived and set up barricades to prevent any accidents while workers cleared up the road.

The inspection reportedly revealed that the material was not mud, but actually foam caused by construction work.

It was reportedly caused by grouting during subway shield tunnel construction.

Officials added: 'The construction created a hole in the ground, which was repaired overnight yesterday, October 28. 'The barricades were removed this morning, and normal traffic has been restored.'