(CNN)- A hospital fire that killed 11 newborn babies in Senegal may have been caused by an electrical short circuit, the country's health minister said Thursday.
Diouf Sarr told local radio station RFM: "When we heard about it, we called the management to find out what happened. We were told that there was a short circuit in the department. The nurses who were there intervened."
Sarr is in Geneva, Switzerland, where he is attending the World Health Assembly conference. He has cut short his trip and will be returning to Senegal immediately, his ministry said.
The fire happened at the Mame Abdou Aziz Sy Dabakh Hospital in the western Senegalese city of Tivaouane, said the country's president, Macky Sall.
"I just learned, with pain and consternation, the death of 11 newborn babies," Sall said in a tweet on Thursday. "I express my profound compassion to their mothers and their families," he added.
CNN has contacted the hospital, but has not yet heard back.
Sall declared a three days of national mourning from Thursday and flags will fly at half mast during this period, a statement from the Presidency said.
The President also launched an investigation to find out the cause of the fire, the country's interior minister Antoine Felix Abdoulaye Diome told reporters during a visit to the hospital overnight on Wednesday.
"Beyond that, he (Sall) asked that we review all the equipment and infrastructure dedicated to newborns who need assistance with machines for their care," Diome said.