BAGHDAD (AP) — A fire erupted Monday evening at a hospital in southern Iraq, sending smoke through a maternity ward and killing four babies who had been born prematurely, health officials said.

The fire started at a pile of debris belonging to a construction company working on renovations at Women and Children’s Hospital in Diwaniyiah, Iraqi Health Minister Saleh al-Hasnawi told journalists at the scene.

The hospital building did not burn but it was filled with smoke, and the four infants died of chest problems as a result of smoke inhalation, Al-Hasnawi said. Some other patients suffered minor injuries.

Iraq’s Red Crescent Society said in a statement that its teams successfully evacuated 150 children and 190 relatives from the hospital. The Red Crescent said the fire might have been triggered by an electrical problem.

Prime Minister Mohammed Shia al-Sudani’s office directed local authorities and the health ministry to open an investigation into the circumstances of the fire, the state-run Iraqi News Agency reported. Officials overseeing the hospital were suspended pending the outcome of the investigation.

Electrical fires, often due to inadequate maintenance and substandard wiring, pose a recurrent threat in Iraq, with the absence of proper fire escapes further compounding the risk. Construction companies and providers of building materials often neglect safety standards, contributing to the hazards.

In 2016, a fire ripped through a maternity ward at a Baghdad hospital overnight, killing 12 newborn babies.

More recently, in September, more than 100 people died in a blaze ignited by fireworks during a wedding ceremony in the northern Iraqi town of Qaraqosh.