RIO DE JANEIRO (AP) — The Rio de Janeiro Olympic Games could prove deadly for the city's poor black people, a delegation of U.S. activists from the Black Lives Matter movement and local activist groups warned Wednesday.

The American activists were on a four-day visit to Rio aimed at highlighting the risks posed by the giant Olympic security apparatus in a country where a United Nations report has concluded law enforcement officers are responsible for a "significant portion" of the nearly 60,000 annual violent deaths.

During the Aug. 5-21 games, some 85,000 soldiers and police will be on patrol in a bid to secure this notoriously dangerous city for the 10,000 athletes and the 350,000 to 500,000 foreigner spectators expected to flood in for the games. That's roughly twice the security contingent at the 2012 Summer Games in London.

But while the mammoth security apparatus may help insulate foreign visitors from the armed muggings, carjackings and drug gang shootouts that are a regular part of life in Rio, the U.S. activists and their local counterparts warned that the increased police presence could result in a spike in police killings.

"We are learning about Olympic construction costs, and dirty water and Zika and crime, but I want the world to know about the horror that is the police killing citizens as part of Olympic preparations," said Elizabeth Martin, a Massachusetts woman whose nephew Joseph was shot to death in 2007 by an off-duty police officer while celebrating his 30th birthday in Rio.

Brazil Police Watch, the group Martin founded following Joseph's death, organized the trip.

The six American activists began their visit to Rio with an emotionally charged meeting with families of local victims of police violence, community leaders and anti-racism activists. Speaking through interpreters, the two groups shared their personal stories and discussed similarities between the black experience in Brazil and in the U.S., with both groups complaining of racial profiling, police killings and the criminalization of poor communities.

"It's important that we stand with each other because we know this violence is connected," said Daunasia Yancey, a Black Lives Matter activist from Boston. "Anti-black violence is global and our resistance is global."

She said that in both the United States and Brazil, police killings of black youths are systemic problems. It's "not just a case of one bad cop. This is a system of policing, this is the way policing works," she said.

Monica Cunha, a Rio resident whose son Rafael was killed by police in 2006, agreed.

In Brazil, Cunha said, "to be black today is to be marked" for death, often at the hands of law enforcement officers.

While the exact extent of police killings in Brazil remains murky, human rights campaigners and international organizations alike have long accused the South American nation's police of routinely carrying out summary executions — often officially explained away as suspects "killed while resisting arrest."

Amnesty International's Rio chapter estimates police were responsible for one of every five slayings in the state in 2015. The human rights watchdog also says police killings rose in Rio state around 40 percent during the 2014 World Cup soccer tournament.

The Black Lives Matter activists said that more than 600 people were slain by police in the U.S. so far this year.

During the meeting, controversial police killings in both the U.S. and Brazil peppered the conversation: Alton Sterling in Baton Rouge, Louisiana; Philando Castile in Minnesota; Michael Brown in Ferguson, Missouri; the 1993 massacre of eight street children outside Rio's Candelaria church; the December killing of five youths in a Rio suburb when police opened fire on their car.

John Selders, a pastor from Hartford, Connecticut, said the commonalities between the plight of black people in Brazil and the U.S. create a bond that transcends language and cultural barriers.

"You are not alone here in Brazil," Selders said, as an interpreter echoed his words in Portuguese. "We are you. You are us. We are one people."