A fire erupted early Wednesday at a nursery for newborns at a major government hospital in Pakistan’s capital, killing 14 babies, according to hospital officials and the government.

The nursery at the Pakistan Institute of Medical Sciences housed at least 15 newborns when the fire broke out, hospital officials said.

At least one baby was rescued.

Rescue officials said the fire began at about 6:45 a.m., apparently after the compressor of an air-conditioning unit exploded inside the nursery, which is part of the hospital’s gynecology ward.

Firefighters quickly responded and extinguished the blaze, and rescue teams were carrying out cooling operations at the site, local media reported.

A hospital spokesperson did not immediately respond to calls seeking comment.

Prime Minister Shehbaz Sharif expressed sorrow over the deaths and ordered an immediate investigation.

A statement from his office confirmed that 14 newborns had died.

“A tragedy involving children is an irreparable loss,” Sharif said.