Six men and three women have died in a blast at an explosives factory near the Brazilian city of Curitiba, in southern Paraná state, emergency officials say.

The explosion happened on Tuesday morning local time when a number of people were on shift in the factory.

Seven people were also injured and emergency personnel with sniffer dogs searched for the nine missing workers, but given the devastating damage at the site, Paraná's security minister later announced that there was "no longer any hope of finding survivors".

The company that owns the factory, Enaex, said it was investigating what could have caused the explosion.

The blast in Quatro Barras, near the state capital, Curitiba, happened just before 06:00 local time (09:00 GMT).

Residents from nearby towns reported being woken up by the sound.

"Within a radius of approximately 1.5km (0.9 miles), we have houses that were hit, with broken windows, damaged structures, and a huge shock wave," a spokeswoman for the fire department said.

She added that the blast had opened up a crater at the site.

Enaex makes explosives for civilian purposes used in construction and mining.

The firm expressed its condolences to the families of the victims and said it would work with the relevant authorities to clarify what had caused the explosion.

The local authorities said that the firm had all the necessary licences to operate at the site, where it had been operating for five decades.