(CNN) -- Twelve people, including two police officers, were killed Saturday in a gun battle between two rival drug gangs in a slum in northern Rio de Janeiro, a state spokesman said.
The spokesman, Marcos Benjamin, did not say who the other victims were.
He said the officers died when their helicopter was shot down over the neighborhood known as Morro dos Macacos. Residents set eight buses on fire during the clashes in an attempt to divert the attention of police, Benjamin said.
Tarso Genro, a spokesman for the Ministry of Justice, told Record TV that the government would make resources available to "continue this fight."
Sergio Cabral, governor of Rio de Janeiro state, where Rio is located, told the network he was "very sad" over the deaths of the police officers.
Last year, a wave of violence in Rio led to protests in December by a group called Rio de Paz.
The group said 9,000 people had been slain since January 2007. Many of the deaths were caused by clashes among drug traffickers fighting for territory in Rio's slums and poor neighborhoods, said the group's president, Antonio Carlos Costa.
In February, police killed at least 10 drug-trafficking suspects in all-day shootouts that closed schools and government offices in three Rio neighborhoods.
CNN's Mariane Teixeira contributed to this report