Police spokesman Emerson Massera told journalists police used chemical weapons and rubber bullets after being attacked at the party
Nine people were trampled to death early on Sunday after two suspects firing guns and being chased by Brazilian police entered a party with roughly 5,000 people, according to a police statement.
Police officers were chasing two men riding a motorcycle when suspects fired guns against them in Paraisopolis, a poor neighbourhood of Sao Paulo. The suspects entered a party playing funk music, causing a stampede, the police said.
Police spokesman Emerson Massera told journalists police used chemical weapons and rubber bullets after being attacked at the party.
He said the police opened a probe to check if the officers' actions were appropriate.
Sao Paulo Governor Joao Doria said there will be an investigation to clarify what happened.
The police spokesman said 38 police officers and 14 police cars were used in the operation.
Another seven people were injured and taken to the hospital.
The statement said police were chasing the men because they were disturbing the neighbourhood. No suspect has been arrested yet.