"They were stoning cars and barricading roads with tyres and rocks," said Tshwane community safety spokesperson William Baloyi.
All roads surrounding the 22-storey, four block building were cordoned off.
"When police arrived at the scene, angry residents retaliated and began stoning police vehicles," said Baloyi.
"The group of people were unruly and we quickly called for back-up."
Protest over water, electricity
The group, who were protesting against water and electricity issues, then ran into the complex.
"They started stoning the police and emergency services from the flats and we had to use rubber bullets to calm the situation," said Baloyi.
"We then used a loud speaker and warned all residents that we are going to storm the flats and that those who are innocent should come out."
Protestors were asked to surrender with their hands above their heads but none did.
About 400 people came out and police were not sure if the protesters were among them.
"We are now presently searching the flats for those still in there. We are expecting to make some arrests."
Baloyi said when police entered the complex, they found the basement was flooded and the electricity wires were tripping.
Repairmen from the water and electricity department were contacted.
Not paying for services
He said the problem was that many people were staying there illegally and not paying for services.
Police believe the baby was injured when people were stampeding out of the building.
No arrests had been made yet and the flooded basement was being pumped out.
The Schubart Park complex was built by the National Party in the 1970s, and the then beautifully appointed buildings boasted a shopping complex, swimming pools, community halls and underground parking.
Last year, the City of Tshwane deemed the building unsafe for occupation and was due to renovate it.
Mayoral committee member Absalom Ditshoke said overcrowding and non-payment of rent had placed strain on the complex, ownership of which had been placed with the city.
Some flats housed up to 21 people, mostly students or illegal immigrants.
It was unclear if renovation had been carried out on the rundown-building.
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