Emergency workers found a lifeless body Wednesday at a chemical plant in northeastern Spain, bringing the death toll to two, authorities said.

The blast, which took place 115 kilometres southwest of Barcelona on Tuesday evening, also injured eight people.

The dead individual was found buried under debris inside the plant, where a worker has been missing since the Tuesday night blast, Miquel Buch, the regional head of Catalonia's interior department, said.

The explosion was heard as far away as 50 kilometres and shook the walls of houses, residents told a local radio station.

The regional firefighters for Catalonia said 30 firefighting crews worked through the night to combat the massive fire.

A preliminary investigation indicated the force of Tuesday night's blast killed an individual in a nearby neighbourhood when a piece of metal struck his residence. The injured were workers at the plant.

Fire chief Albert Ventosa said Wednesday that the fire is under control and that there is no danger to the exterior of the plant.

Authorities are investigating the cause of what they describe as a chemical accident

Due to the blast wave of the explosion, a person died when a structural element (probably a roof) collapsed from a floor in the Torreforta neighbourhood in Tarragona, local press relates.

Reports suggested that 8 people had been injured in the explosion, at least two seriously, according to emergency services in Tarragona.

Local residents posted videos showing the aftermath of the blast, with flames and a big column of black smoke emerging from an area dotted with big industrial tanks.

Tarragona is a city of 800,000. Since 2015, it has housed a 1,200-hectare chemical hub known as ChemMed which is the largest of its kind in southern Europe.

Quim Torra, Catalonia's president since 2018, assured people not to worry unduly over the cloud of smoke: "There is no toxic element", he told Spanish newspaper El Pais.

Miquel Buch has assured that the confinement could be lifted shortly "if no new data comes out."

There are at least 29 firefighters companies currently working on the extinction of the fire: "We continue to inspect the site for any people trapped" they tweeted.

What we know about the chemical plant

The blaze has happened at Iqoxe company (Industrias Químicas del Óxido de Etileno, henceforth “IQOXE”). It is a petrochemical company that works with ethylene oxide to produce various raw materials for the production of cosmetics, detergents, foams, antifreezes and products for the pharmaceutical industry.

This organic compound is also used to clean surgical instruments.

The company is the only producer of ethylene oxide in Spain with a production capacity of up to 140,000 tonnes per year.

Iqoxe is also engaged in the manufacture of glycol used for the production of polyester.

In July 2019, Iqoxe inaugurated a new derivative plant, which has a reactor "with the latest technology available to increase the production of derivatives by 30,000 tonnes".

According to the company at the time, the new project, which saw 50 new jobs, was a "considerable boost for company growth" and moved the company to be "European leader in ethylene oxide derivatives".

Sources of UGT, the majority union at the Iqoxe plant, confirm that the explosion and fire have taken place in this factory.

According to the union, at the time of the explosion other companies were working on the plant for maintenance. The surrounding plants have activated the self-protection plan (PAU), which has cut communications.

The explosion was caused by highly flammable ethylene oxide, and probably originated in the reactor or in one of the accompaniment lines of the reactor.

The workers of this plant went on strike recently for claims about the labour agreement, which UGT decouples from security reasons.