The City of Sacramento was sued on Tuesday by the top prosecutor of the surrounding county, who said that California’s capital had suffered an “utter collapse into chaos” because city authorities were not doing enough to remove homeless people from the streets.

The lawsuit is the latest sign of mounting frustration over homelessness in California, where encampments have become a fixture of downtown streets and freeway rights of way.

District Attorney Thien Ho of Sacramento County asserted in the suit that lax enforcement of city ordinances had left homeless people to suffer in “Third World” squalor and neighboring residents to endure hazards and threats of violence.

City officials swiftly denounced the suit as a political act driven by disgruntled local business interests and an opportunistic prosecutor who was elected to office less than a year ago.

Even so, the complaint, filed by a Democratic district attorney against a Democrat-led city, highlighted a broadening impatience — even in areas dominated by liberal voters — with homeless camps and with progressive policies and court rulings that have thwarted their removal.

More than 170,000 people are homeless in California, accounting for about one-third of the nation’s homeless population. More than 115,000 of those 170,000 Californians sleep on the streets, in cars, in tents or outdoors in places not intended for humans, according to a federal tally of homelessness conducted last year.

That makes homelessness a more visible crisis in California than in places like New York City, where residents without permanent housing typically live indoors because of right-to-shelter laws. In several large California cities, camps sprawl across sidewalks, overwhelm parks and deter the public from visiting riverbanks and beaches.

Lawyers and activists representing homeless people say the state has failed to provide enough housing for its most desperate residents, and that many working people have been forced to sleep in tents or in their vehicles because they cannot find affordable places to live.

The crisis has made California a regular target for critics, particularly Republicans who point to encampments in San Francisco and Los Angeles as symbols of liberal excess. In recent months, Mayor London Breed of San Francisco, and Gov. Gavin Newsom, both Democrats, have also pointed to homeless camps as a sign of society’s increasing dysfunction.

“It’s just gone too far,” Mr. Newsom said in a Sacramento forum held last week by Politico. “People’s lives are at risk. It’s unacceptable, what’s happening on streets and sidewalks. Compassion is not stepping over people on the streets.”

Where Mr. Newsom differs with Republicans — and with Mr. Ho — is on who is to blame.

The governor has ramped up his criticism of federal judges who have ruled that homeless people have a right to camp if cities fail to house them. In 2018, the Court of Appeals for the Ninth Circuit ruled that cities could not clear people from the streets unless they offer adequate alternative shelter. Since then, a growing body of federal case law has made it exceptionally difficult for municipalities in the nine Western states overseen by the circuit, from Arizona to Hawaii, to enforce laws regulating public camping.

As a result, many California city leaders say they are left to guess what they can legally do, with interpretations varying from county to county. Some municipal leaders have reduced enforcement out of fear of potential legal costs.

Last week, Mr. Newsom went as far as to say that he wanted to challenge the 2018 decision all the way to the Supreme Court, where he hoped that the justices on the conservative-leaning bench would make it easier for states like California to remove encampments legally, or at least would provide more clarity on what was legal. “That’s a hell of a statement for a progressive Democrat,” he said.

Between 2020 and 2022, the number of homeless people in Sacramento County increased by 68 percent, to 9,278, according to the latest federal data. By comparison, San Diego County’s homeless population increased by 10 percent, and Los Angeles County’s, 2 percent.

“Across the nation, Sacramento was one of the places where homelessness grew the most,” said Marisol Cuellar Mejia, a research fellow at the Public Policy Institute of California, which analyzed the data.

Last year, Mr. Ho defeated a more progressive opponent in an election campaign that made homelessness a central issue, drawing support from across Sacramento County, including the liberal-leaning capital city and its more conservative suburbs.

He said in an interview that he became particularly worried after a series of alarming incidents near his office, across from the county courthouse in downtown Sacramento. He said his staff and court workers had been assaulted and threatened by people from the nearby encampments, and that a juror headed to court was chased by an unhoused person wielding a needle.

Citing a survey in July of some 3,000 residents living near 16 encampments around the city, the lawsuit claimed that small retailers near some camps had been driven out of business, and that families residing nearby were afraid to leave their homes.

In the neighborhood around one Sacramento camp, the suit said, youth soccer games had stopped after the occupants of a tent camp took over the fields, unleashing aggressive dogs, occupying bathrooms and strewing the playing fields with hundreds of hypodermic needles. Near another encampment, local residents said that embers from campfires had become such a threat that the fire department had begun conducting fire drills.

The 36-page lawsuit relies on detailed accounts from residents living near encampments in the city, but it does not reference crime data.

Mr. Ho said that Sacramento residents had told his office that their pleas for help from the city had gone unanswered. “What we’re asking to do through the lawsuit is to require and force the city to do its job, to keep the streets clean and safe, to enforce the law,” he said.

Anthony D. Prince, general counsel for the California Homeless Union, called the county’s lawsuit a “dangerous, inflammatory and dishonest escalation of the war against the homeless.” He said politicians like Mr. Ho and Mr. Newsom were scapegoating vulnerable people who lacked housing because of systemic inequities in California and who were more likely to be preyed upon than to bother surrounding neighborhoods.

Sacramento city officials said many of the anecdotes cited in Mr. Ho’s lawsuit were dated, and that the district attorney had ignored city efforts to work together with him on the issue. For most of August, they said, the city had little control over encampments because of a federal court order that temporarily banned the city from moving homeless people in extreme heat.

In an interview, the mayor of Sacramento, Darrell Steinberg, said that the city had deployed an “incident management team” to respond specifically to complaints around encampments, and had stiffened enforcement of local laws governing critical infrastructure, private property and access to sidewalks. A former legislative leader with long expertise in mental health issues, Mr. Steinberg helped the governor place a measure on the March 2024 ballot that will ask voters to redirect more mental health funds into housing and treatment for homeless people.

A statement from his office dismissed Mr. Ho’s lawsuit as “a performative distraction” from the hard work necessary to address homelessness.