Image copyright AP Image caption Firefighters recovered four bodies from the wreckage of the aircraft

Four police officers have died after their helicopter crashed over Rio de Janeiro's notorious City of God favela.

In video footage of the crash, sustained gunfire can be heard before the helicopter drops from the sky, narrowly missing a main road.

The helicopter was giving support to a police operation against gangs in the favela, according to police.

Police reportedly began a large scale operation on Sunday in western Rio, with arrests and seizures of drugs.

'Fell in a ditch'

There had been several clashes during Saturday between police and criminal gangs operating in the City of God favela area.

Firefighters removed the bodies of the victims from the wreckage, which could be seen in the footage crumpled and smoking.

A police spokesman said that forensics officers were examining the wreckage to determine the cause of the crash.

Image copyright Reuters Image caption Police had been carrying out anti-drugs operations on Saturday in the City of God favela

One man who saw the incident, Thiago Duarte, told Associated Press: "We were here watching the shooting in the woods... Suddenly a friend shouted 'the bullets reached the helicopter, it's going to come down!'

"It was clear that [the pilot] was trying to do everything to avoid falling over the shanty town or on the expressway, so it turned back and fell into the ditch."

On Sunday, police backed by an armoured vehicle carried out further operations, with at least two people arrested, another injured and a number of drugs seized.

Rio state security secretary Roberto Sa said police were investigating a territorial dispute between members of two favelas in western Rio.

If the helicopter was shot down by gang members, it would not be a first for the city, which hosted the 2016 Olympics.

In 2009, drug traffickers opened fire on a police helicopter, causing it to explode and crash land on a football pitch, killing both pilots.

Violence has been on the rise in Rio over the past two years following the failure of a 2010 programme to rid the favelas of drug gangs.

A total of 3,649 murders were reported in 2016 up until the end of September, a rise of almost 18% on the same period last year.</s>The former governor of Rio de Janeiro state was arrested on Thursday as part of a corruption investigation linked to a World Cup project and other works worth billions of dollars, in a blow to Brazil’s ruling party that may fuel political instability.

Federal prosecutors accused Sergio Cabral, 53, of leading a criminal organization that took 224 million reais ($66 million) in bribes from construction firms in exchange for infrastructure contracts from 2007 to 2014, the years he served as governor.

The projects included the renovation of the famed Maracana soccer stadium, where the final match of soccer’s 2014 World Cup was held, along with public works in some of Rio’s biggest slums and the construction of a major highway around the city’s outskirts.

Federal police and prosecutors are also investigating several infrastructure projects related to this year’s Olympic Games in Rio de Janeiro. They have not yet taken any action on those inquiries.

As Cabral, the most powerful figure in Rio politics for the past decade, was driven out of the garage of his apartment building on Thursday morning in a black federal police SUV, dozens of people who had gathered hurled insults as TV cameramen and photographers encircled the vehicle.

Cabral made no comment. His lawyer declined to comment when reached by phone.

Following anti-corruption rallies, Cabral resigned his governorship in April 2014 with nine months left in his second term.

Cabral’s arrest capped the decline of the Rio de Janeiro branch of the Brazilian Democratic Movement Party (PMDB), President Michel Temer’s party, which was voted out of the city government last month amid graft probes into a number of its prominent figures.

“It creates a nervous environment which could delay our economic recovery if investors get cold feet,” a presidential aide told Reuters. The aide also said the Rio state government was close to insolvency, and the Temer administration fears a domino effect hitting the finances of other Brazilian states.

Cabral is the latest high-profile politician to be arrested in a two-year corruption probe known as operation “Car Wash,” which began by unraveling a massive political kickback scheme at state-run oil company Petrobras.

Cabral was a close ally of former President Dilma Rousseff, removed from office in August on charges of illegally using money from state banks to bankroll public spending, and former President Luiz Inacio Lula da Silva, whose trial on corruption charges in the Petrobras probe begins on Monday.

Executives from several construction firms have turned state’s witness and the companies have signed leniency deals. That has provided testimony about endemic corruption in Brazil’s political and business establishment, igniting dozens of new inquiries like the one resulting in Cabral’s detention.

Testimony from executives of the construction and engineering firms Andrade Gutierrez and Carioca Engenharia formed the basis of Thursday’s arrests, prosecutors said.

“There are strong indications of the cartelization of works executed with federal resources, through the payment of bribes to Sergio Cabral and other (state) employees,” federal prosecutor Lauro Coelho said.

Operation Car Wash also stoked the political upheaval that ultimately toppled leftist president Rousseff.

“Cabral’s arrest is unlikely to hit the Temer administration directly, but it will fuel political instability as the investigation seems to be setting its sight on the PMDB and other parties,” Leonardo Barreto of Brasilia-based consultancy Factual Informacao e Analise said.

Cabral’s arrest came a day after another former Rio governor, Anthony Garotinho, was arrested for alleged voter fraud in a state struggling with a severe fiscal crisis and austerity protests.
Former Rio de Janeiro governor Sérgio Cabral is arrested in corruption probe.