At least 45 people have been killed and more than 100 others injured after a factory collapsed in the industrial area of Lahore, in Pakistan's east.

Muhammad Usman, a local administrator, said about 150 workers, including the owner of the factory, were at the three-storey building at the time of collapse on Tuesday.

Rescue official Jam Sajjad Hussain said dozens of other labourers remain trapped under the rubble.

Hussain said emergency teams are using heavy machinery to remove the bodies and look for survivors.

Army personnel have been deployed to the site of the factory to help in the rescue efforts, the military said.

Dozens of the workers' families rushed to the scene of the incident to learn about the fate of their loved ones.

Army personnel have been deployed to the site of the factory to help in the rescue efforts, the military said [Kamal Hyder/Al Jazeera]

Provincial spokesman Zaeem Qadri told reporters that progress was slow because the factory was at the end of a narrow lane making it difficult for excavators to reach the site.

He added that an emergency has been declared at all local hospitals. 

Chief doctor Zia Ullah of Jinnah Hospital, where some injured have been taken, said most of the victims were young workers, with many suffering head injuries and fractured limbs.

The cause of the collapse was not clear, but it comes more than a week after a magnitude-7.5 earthquake hit Pakistan, killing 273 people and damaging nearly 75,000 homes across the country.

Pakistan has a poor safety record in the construction and maintenance of buildings.

Last year, a mosque collapsed in the same city, killing at least 24 people.

More than 200 people lost their lives to collapsed roofs following torrential rainfall and flooding in 2014.

In 2012, more than 255 workers were killed when a fire tore through a clothing factory in Karachi, one of the deadliest industrial accidents in Pakistani history.

Rescue officials said dozens of labourers remain trapped under the rubble [Kamal Hyder/Al Jazeera]

Source: Al Jazeera And Agencies