The deadly explosion occurred at a house where fireworks were being produced in Ban Pho Tha Sai, tambon Ban Pho, about 11am.
Police said nine people died in the explosion. Another person was injured and was rushed to hospital. All were Thai women. One dead victim was eight-months pregnant.
The explosion destroyed two houses and a car, reports the Bangkok Post.
Local officials set up an aid centre at Wat Pho Tha Sai in tambon Ban Pho.
The cause of the explosion is under investigation.
Suphan Buri was also the site of a fireworks factory explosion in January 2024 in which 23 people were killed. A few months before that, a huge blast at a fireworks warehouse in Narathiwat killed 12 people.
The Ministry of Industry said in January last year that it would look to amend laws on setting up fireworks factories.