An explosion at a fireworks factory in northwestern Turkey on Friday killed four people and injured at least 97 others, officials from Turkey said.

There were 186 workers at the factory outside the town of Hendek, in Sakarya province, Health Minister Fahrettin Koca told reporters.

According to the reports, explosion killed four workers while 97 others were hospitalized. Sixteen of the injured were later discharged.

The cause of the blast at the factory, which is away from residential areas, is under investigation.