The fire broke out on the 20th floor of the Cottingley Towers flats, with people reported trapped, according to the fire service.
The fire service was called shortly after 10.30am today. Crews from eight different fire stations were sent out the scene, with eight firefighters donning breathing apparatus.
Four casualties were brought to safety by firefighters and left in the care of paramedics.
First bus services 54 and 55 are diverting away from the area.
The 1970s-built block and its neighbour Cottingley Heights are owned by Leeds City Council and contain socially rented flats.
They are 236ft high and both have 25 floors. The towers were once the tallest buildings in Leeds.