Ten people have been confirmed dead following Tuesday’s fire outbreak at Afriland Tower on Lagos Island, with officials revealing that toxic smoke from a burning lithium battery inverter system caused most of the fatalities.

Emergency responders said the fire started in the inverter room, and thick smoke quickly spread through the building, including emergency exits. Videos showed some workers jumping from the high-rise to escape, while others were rescued with ladders.

The victims — staff of the Federal Inland Revenue Service and United Capital — reportedly died in hospitals after suffering severe smoke inhalation. Officials said the smoke, laden with carbon monoxide, displaced oxygen in the building, leaving many unconscious before rescue teams arrived.

No bodies were recovered at the scene, and those who received prompt treatment survived, according to medical personnel.