Pretoria police on Wednesday fired rubber bullets and used pepper spray on protesting Schubart Park residents.
Earlier in the day, hundreds of residents took to the streets following a week-long electricity problem in the area.
Angry locals gave Tshwane officials until 2:30 pm to restore the power.
But when the municipality failed to repair the problem, residents took to the streets for a second round of protests.
Police have now made their way into the complex as demonstrators throw rocks and bottles at authorities.
One man was carried out of the complex by several people after he sustained a wound to his eye.
Police reinforcements have been called into the area.
Authorities escorted several women and children from the volatile complex.
Emergency workers were called in to extinguish a fire on the fourth floor after locals set fire to rubbish in the stairwell.