At least 13 children, mostly newborns, have died after a fire broke out at the gynecology ward of the largest hospital in Pakistan’s capital, police told CNN.

The fire broke out in a nursery for newborn babies at the Pakistan Institute for Medical Sciences (PIMS) in Islamabad, the sources said. The blaze appears to have been triggered by an air conditioning compressor explosion inside the nursery, according to rescue sources.

Hospital authorities were able to rescue one child, the sources said. The blaze has also left some babies in critical condition and the death toll could rise, they added.

Islamabad’s Chief Commissioner Sohail Ashraf said an emergency fire call was made just before 7 a.m. local time Wednesday.

Rescue teams rushed to the scene and “controlled the fire,” Ashraf said in a post to X.