More than 100 workers were injured in a factory fire in the town of General Trias, Cavite province, about 25 miles south of Manila, Philippine authorities said Thursday.

Huge plumes of smoke continued to emanate from the complex, with onlookers standing more than 100 yards away still able to feel the heat, a journalist said.

Many workers are feared to still be trapped in the Japanese facility, one of the biggest factories in the province which employs around 6,000 employees to manufacture housing materials.

Cavite Governor Jesus Crispin Remulla told the Inquirer newspaper Thursday morning that about 40 people are still being treated in hospital, with some of the victims suffering burns to about 75 to 90 percent of their bodies.

The fire began as employees were changing shifts at around 6 p.m. local time, the governor said.

The fire is believed to have spread quickly due to flammable materials in the factory, the Philippine Star newspaper reported.

Authorities are continuing to investigate the origin of the blaze.

Telesur