At least 10 people have been injured, four seriously, after a grain silo exploded and was engulfed in a fireball in the southern port area of Strasbourg, France.

Four people were seriously injured and taken by helicopter to the Hautepierre hospital in Strasbourg while six others were treated for injuries and shock at the site, owned by agri cooperative Comptoir Agricole, reported the France 3 news channel on 6 June.

Stéphane Kunz, a truck driver who was near the site at the time of the incident, told France 3: "I heard a big boom, and thought it was the trailer. Then I saw a fireball burst a few metres from my vehicle and a lot of debris.”

The cause of the explosion and the subsequent fire was not clear but, according to L’Alsace.fr news outlet, it was suspected that sparks from welding operations may have ignited asbestos fibres that were possibly present in the silo’s roof structures.

According to the news report, 108 firefighters and 60 rescue and fire service machines took part in the rescue operation that saw an area of 200m around the silo cordoned off and schools in the area going into lockdown.

Comptoir Agricole is a French agri cooperative that operates in several sectors, including oilseeds, animal feed, cereals, vegetables, hops and grape farming.