Police and rescue officials say a gas explosion has ripped through an apartment building in Pakistan’s largest port city of Karachi, killing at least 16 people, after part of the structure collapsed on the first day of Ramadan. Several people were also injured in the pre-dawn explosion on Thursday in Karachi, the capital of Sindh province, local police chief Rizwan Patel said. Rescuers were still removing rubble to search for any survivors trapped under the debris, he said. Most houses and apartment buildings in Pakistan are supplied with natural gas for cooking. However, many households also rely on liquefied petroleum gas cylinders because of low natural gas pressure, and such incidents are common.