LONDON — London Mayor Sadiq Khan declared a “major incident” Saturday as the omicron variant of the coronavirus surged through the United Kingdom’s capital.

The impact of the rapid spread of the variant was already felt across the city with

KARACHI, Pakistan — A powerful gas explosion in a sewage system in Pakistan’s largest city, Karachi, killed at least 12 people and injured 11 others Saturday, police and a health official said.

Police spokesman Sohail Jokhio said the blast was