An inferno at a three-story clothing store in the southern Philippines early Wednesday killed 17 employees, most of whom were women who were asleep and trapped on the top floor, officials said.

The fire in the Butuan city store broke out at 3:55 a.m. and raged for five hours. Firefighters and police scouring the gutted building found 17 bodies, said city police chief Pedro Obaldo.

Store employee Mylene Tulo, who escaped with two co-workers, said she was roused from sleep as the fire spread rapidly in the third-floor office where they slept. Amid the inferno and yells for help, she managed to dash out with her colleagues. They sustained minor burns on their arms.

“We wanted to rouse others from sleep, but the fire was already too strong,” a stunned Tulo said.

At least 20 employees, mostly women, were sleeping at the store when the fire broke out, Obaldo said. Many stores in the Philippinesallow their employees to sleep over, especially those with faraway homes.

Relatives and friends, most of them in shock and tears, gathered in search of loved ones in front of the building, where police stood before body bags with the victims’ remains.

Obaldo said investigators were trying to determine what sparked the fire and if the owners violated fire regulations.

The building in Agusan del Norte province in the southern Mindanao region was a theater before being turned into a commercial center with several stores, including the Novo Jeans and Shirts, where most of the victims died.

A lack of firefighting equipment and personnel coupled with safety violations has resulted in major fire disasters in the Philippines, especially in shantytowns. A 1995 inferno that gutted the Ozone Disco Pub in Manila, the capital, killed 162 people.

Butuan is a city of more than 300,000 about 790 kilometers (500 miles) southeast of Manila.