At least five persons died and more than 25 were injured in a blast inside a firecracker manufacturing unit in India's northern state of Punjab on Thursday, confirmed a local cop over the phone.

The factory was located near a village in Punjab's Sri Muktsar Sahib district. All the victims were laborers engaged in the manufacturing and packaging of firecrackers.

The two-storey building collapsed in the blast, trapping the workers under its debris.

According to the police officer, those injured had been admitted to nearby government hospitals, and a probe was ordered to determine the cause of the blast.

Rescue work was still on, and efforts were being made to ensure that no one was trapped under the rubble.

xinhua