Seven women and two children were killed, with dozens of others trapped under rubble when a factory collapsed in Pakistan's city of Lahore on Monday, officials said.
The three-storey building used to manufacture veterinary medicines came crashing down, probably the result of a boiler and a gas cylinder explosion at the premises in the congested Multan Road area, police said.
Rescue workers dug through the rubble with bare hands, desperate to answer trembling cries for help from people trapped beneath concrete slabs as sobbing relatives urged rescuers to do everything possible to recover their loved ones.
Police said the Orient Labs (Private) Limited factory was illegal as it was without the proper registration, and they were hunting down its three partners.
The accident at the 25-year-old factory will likely highlight poor safety procedures among Pakistani manufacturers and, with young boys among the dead, the use of child labour.
Senior police official Shoaib Khurram said nine people were confirmed dead and 16 others wounded, as rescue workers turned on flood lights to carry on the recovery operation after dusk.
Officials identified the dead as seven women and two boys, aged 12 and 14.
An AFP correspondent saw rescue workers carry out one of the dead children and put his body into an ambulance to be driven to hospital.
Different officials estimated that there were between 35 and 50 people still buried under the rubble. Most of them were believed to be women and children, who were hired to pack up the medicines.
Mohammad Akram, 50, said he ran to the site shortly after 8:00 am (0300 GMT), desperately worried about his 10-year-old son, Asad, a packer.
"I came here rushing and weeping but luckily my son has been rescued. He is injured and alive. But my 12-year old nephew is still missing."
The main working hours were 8:00 am to 5:00 pm, but employees were quite often required to work late into the night as well, Akram said.
The rescue effort was hampered by narrow lanes and it took time for heavy cranes and excavators to reach the area.
"It's a big disaster. It is too early to say when we'll finish. We want to recover alive as many people as possible," said rescue worker Ahmed Raza.
Workers and volunteers used everything they could -- hammers, axes, chisels and shovels -- to shift the rubble and pull out the injured, coated in dust, as relatives stood by, sobbing, and a crowd of local residents gathered to watch.
One slightly injured girl pulled out of the rubble was too frightened and panicked to tell reporters and rescue workers what she remembered.
A 55-year-old housewife refusing to give her name accused the government of providing no security to taxpayers.
"There are factories working illegally in residential areas. We have lodged complaints in the past but who will listen to us?" she said in desperation.
As dusk fell, rescuers switched on flood lights with the help of a generator, preparing for a night of painstaking work.
"The search will continue throughout the night. We have to be very careful, it is the question of human lives," said police official Ghulam Mehmood Dogar.
A small group of about 15 to 20 workers protested at the site, carrying the red flags of Pakistan's Labour Party and shouting: "Who is accountable for the (deaths) of these innocent workers? We want an answer."
Eight million people live in Lahore, 253 kilometres (160 miles) southeast of the capital Islamabad. It is considered Pakistan's cultural capital and perhaps the most liberal city in the conservative Muslim country.