A factory near the city of Lahore, Pakistan, suddenly collapsed into rubble on Wednesday, leaving at least 18 persons dead so far. It is believed that many more people may still be trapped beneath the rubble of what was once a four-story factory that made plastic bags.

The factory had been undergoing renovations and expansion and the cause of the building collapse is unknown at this time, according to The New York Times. Thus far, at least 70 or so factory workers have been uncovered and removed from the rubble. Eighteen dead bodies have so far been recovered and authorities believe as many as 100 other workers or more may still be trapped or dead.

Rescue workers are using shovels and some construction cranes have been brought in to assist in the rescue. The Pakistani army’s engineers are also on the scene, and all of Lahore’s hospital have been put on special alert. The factory is operated by the Rajput Polyester Factory and is located in an industrial complex just outside the major Pakistani city of Lahore, which is the capital of the Punjab Province. The company currently employs 250 workers.

Other heavy construction equipment has been brought in to aid in the rescue efforts. Authorities on the scene say that the factory had been deteriorating over the years and was in fairly run down condition before it collapsed. The additions and improvements being made to the factory included a new fourth floor that was nearly completed. Speculation is the added weight, or the roof of the fourth floor, may have caused the collapse of the factory itself.

The factory building had also developed a maze of cracks from a recent earthquake that hit the region a month ago. The prime minister of the country has tried to reassure and comfort the nation and a formal inquiry has been launched by the government. It has renewed calls for stricter enforcement of building codes in Pakistan. Construction codes are not too closely followed in a country that sits right in the middle of an active earthquake zone.