Four people were injured after a two-alarm fire involving lithium-ion batteries broke out at a Toronto Community Housing building Wednesday morning.

Toronto firefighters were called to a fourth-floor unit on George Street near Dundas Street East shortly before 6 a.m. The fire was extinguished, but four people were injured. Three were assessed by paramedics at the scene, while a fourth went directly to hospital for treatment.

Toronto Fire Chief Jim Jessop issued a warning about the potential dangers of lithium-ion batteries after three battery-related fires were reported across the city within a 24-hour period.

Fire officials said six micro-mobility devices, such as e-bikes and e-scooters, were inside the unit where Wednesday’s fire occurred. It remains unclear what specific role the batteries played in the fire.