Airstrikes in Syria's largest city killed more than a dozen people at a well-known hospital, says aid group Doctors Without Borders, adding that the violence killed one of the last pediatricians working in Aleppo.

"We are outraged at the destruction of Al Quds hospital," the group said in a tweet today, saying that the facility included an intensive care unit and an emergency room.

At least three doctors who worked at the hospital are among the 14 bodies that have been recovered, according to Doctors Without Borders, which says the death toll is expected to rise.

"Opposition activists blame the government and say the hospital's location was well-known," NPR's Peter Kenyon reports. "The fatalities come as the U.N. envoy for the Syrian talks urges all sides to renew efforts to implement a cease-fire that he describes as barely alive."

That envoy, Staffan de Mistura, tells NPR's Morning Edition that the new violence raises the risk that opposing sides in Syria's conflict will return to the "horrible habit" of war.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.