Local reports said the state-run airline's Airbus A320 was travelling from Lahore.
"The plane PK 8303 with 99 passengers and 8 crew members has crashed," said a spokesman for the national carrier.
It is feared there may be more casualties as the plane came down on houses in Model Colony in the city.
A spokesperson for the Pakistan Armed Forces tweeted that helicopters were being used in the search and rescue effort and that paramilitary troops had reached the site, alongside civil administration.
https://news.sky.com/story/pakistan-international-airlines-plane-with-107-passengers-on-board-crashes-in-karachi-11992696