Manila - At least three people were killed in an explosion Thursday that rocked a firecracker factory just outside the Philippine capital, a police report said.

The blast occurred shortly before noon inside the Starmaker Fireworks factory in the village of Conchu in Trece Martires City in Cavite province, 25 kilometres south of Manila.

Alvin Mojica, vice mayor of Trece Martires, said more than 40 people were also reported injured in the explosion.

Mojica said thick smoke prevented firefighters from entering the factory. (dpa)