At least 14 newborns died Wednesday after a fire broke out in a nursery at a major government hospital in Pakistan’s capital Islamabad, officials said.

The blaze erupted at around 7 a.m. local time (0200 GMT) on the third floor of the Maternal and Child Health Ward at the Pakistan Institute of Medical Sciences (PIMS), where 15 babies were being treated.

The Islamabad administration initially said the fire was brought under control shortly after it broke out and that 14 severely burned babies were transferred to an intensive care unit.

Prime Minister Shehbaz Sharif’s office later confirmed the deaths.

PIMS spokesperson Dr. Aneeza Jalil said the fire appeared to have been caused by a short circuit, according to Pakistan’s Dawn newspaper. Other local media reports said a malfunction in the hospital’s air-conditioning system may have triggered the blaze.

Sharif expressed deep sorrow over the deaths and ordered an immediate investigation into the incident.

“Such a situation involving children is irreparable. The causes of the incident should be thoroughly examined, those responsible should be identified, and the strictest possible action should be taken,” the Prime Minister said.

The Islamabad administration formed an inquiry committee headed by the additional deputy commissioner general to determine the circumstances surrounding the fire.

The committee will also examine whether negligence or failures in the hospital’s safety systems contributed to the deaths and identify those responsible. (Anadolu Agency, but headline rejigged)