People trapped in the rubble of a deadly factory collapse in eastern Pakistan Thursday desperately called for help on their cell phones as the hours ticked by, Reuters reports.

At least 18 people died, and 50 others were hurt, according to Jam Sajjad Hussain from the state rescue agency.

Hussain says rescuers worked overnight and saved more than 100 people from the rubble of the building, which collapsed Wednesday on the outskirts of Lahore city. The building was under construction.

One trapped worker called a local television station, according to Reuters. He said, "I can hear the rumble of heavy machines, which gives me hope that I will come out alive."

Many of those trapped were in the building's basement, Reuters adds. More than 200 workers were inside the building when it caved in.

The cause of the collapse is yet to be determined. It happened just over a week after a magnitude-7.5 earthquake hit Pakistan, killing 273 people and damaging nearly 75,000 homes.

Some survivors claim the factory's owner had ignored requests to halt construction after cracks emerged in the walls following the quake. A government official told Reuters the factory's owner died in the collapse.

The Associated Press contributed to this report.