RIO DE JANEIRO — If battling pickpockets were an Olympic sport, the Brazilian authorities might qualify for a medal.

In the face of soaring street crime, the state government has deployed a security force of 85,000 in Rio, among them 23,000 soldiers who stand sentinel at busy intersections or cruise the streets in military jeeps, their weapons aimed menacingly at the sidewalk.

In one of the more intriguing displays, a Brazilian naval ship has been patrolling along the city’s famed Ipanema Beach.

Still, the overwhelming show of force has not exactly vanquished crime. The chief of security for the opening ceremony was mugged at knifepoint on Friday night as he left Olympic Stadium; a stray bullet landed in the equestrian arena’s media tent on Saturday, just missing a New Zealand sports official; and on Saturday night, Portugal’s education minister was assaulted as he strolled along Rio’s upscale lagoon, site of the rowing competition.

In their preparation for the Olympics, Brazilian officials confronted a number of challenges that had spooked some international visitors, including fears over the Zika epidemic, the threat of terrorist attacks and unflattering news media reports that drew attention to the city’s polluted waters.

But it is the recent surge in street crime that has most unnerved city officials and residents, who worry that an embarrassing spike in lawlessness could dent the pride and euphoria that have taken hold here since the Summer Games began on Friday night.

Despite the most recent incidents, including a bomb scare Saturday near the finish line of a men’s cycling race, most visitors and residents say they feel safe. “This must be the safest place in Brazil right now,” said Isabela Carvalho, 46, an ice cream vendor, as military police officers sped by on motorcycles, sirens wailing.

But the show of force has also drawn criticism from human rights activists who fear that overly aggressive policing might lead to abuses, especially in the city’s low-income communities, known as favelas.

Last week, a joint police and military operation in one such neighborhood, Complexo do Alemão, left two people dead.

Officials have sought to reassure visitors, pointing out that the security force is more than twice the number dispatched during the London Olympics of 2012. They also note that Rio has successfully hosted other large sporting events, including the 2014 World Cup.

The city’s security woes have been exacerbated by a severe budget crunch, which has hampered the government’s ability to pay police officers. The sense of crisis was underscored in June, when the state government declared a “financial calamity.”

In recent weeks, police officers who said their salaries had been delayed or only partially paid demonstrated at Rio’s international airport, holding up signs for arriving passengers that read, “Welcome to hell.”

Fábio Neira, a civil police commissioner, said the late paychecks had dampened morale. “This creates a huge financial difficulty for us because you have to pay your bills, electricity and rent at the beginning of the month,” he said in an interview.

Although the federal government subsequently provided an $850 million bailout to pay for security costs during the games, Neira said the money did not cover overtime worked in May or June.

Working conditions, he added, remain abysmal, noting that some police stations lacked pens, toilet paper or money for gas.

Although the Brazilian news media tends to focus on brazen street robberies or violence that occurs in the city’s wealthier neighborhoods, experts say it is Rio’s poor residents who bear the brunt of increased crime.

Professor Julita Lemgruber, coordinator of the Center for Studies on Public Security and Citizenship at Candido Mendes University in Rio, said the rise in street crime was partly tied to failed efforts to improve public security in the city’s favelas.

In 2008, the state of Rio de Janeiro began an ambitious initiative, creating Police Pacification Units, which were responsible for combating drug gangs that had been operating with impunity. The program, which also relies on community policing and social work, is cited in Olympic documents as an important factor in addressing the city’s long-standing security concerns.

Atila Roque, the executive director of Amnesty International in Brazil, said the program has been riddled with abuse and had exacerbated tensions between the police and residents, some of whom have called for an end to the effort.

Last year the police were responsible for 20 percent of the city’s homicides, according to Amnesty International, which used data from the state’s Public Security Institute. There were 645 police killings last year, compared with 400 in 2013. The number of those who died at the hands of the police between April and June of this year doubled from the same period last year, according to the data.

Most of the dead were young black men.

One of the communities hit hard by police violence is Maré, a sprawling favela that sits between Rio’s international airport and the affluent neighborhoods of Ipanema and Copacabana. The authorities have long struggled to contain the violence spawned by warring drug traffickers and militia groups. In the months before the World Cup, the army occupied the community for a year.

Eliana Sousa Silva, who was raised in Maré and is the founder of a local nonprofit group, said police operations there became more frequent as the Olympics approached. Late last month, journalists living in the neighborhood reported three straight days of police operations that involved heavy gunfire.

“The Olympics, like the World Cup and other mega events in Rio, are always a tense moment for residents of Maré,” she said, adding that police operations are often heavy handed. “The government needs to ensure nothing happens, in order to show Rio to the world.”