Leaders in Minnesota and Democrats across the country are demanding that federal immigration officers leave the state, after a Border Patrol agent fatally shot a man in Minneapolis on Saturday.

The shooting set off further clashes with protesters in a city already shaken by another shooting death weeks earlier.

Minnesota Governor Tim Walz called the shooting "horrific" and demanded state authorities lead the investigation.

"The federal government cannot be trusted to lead this investigation. The state will handle it," he told a news conference.

However, Drew Evans, superintendent of the Minnesota Bureau of Criminal Apprehension, said that the US Department of Homeland Security denied his agents access to the scene after the shooting, The Associated Press reported.

"We had a signed warrant and we were still denied access," he said.

The DHS characterized Saturday's incident as an attack, saying a Border Patrol agent fired in self-defense after a man approached with a handgun and violently resisted attempts to disarm him.

The DHS pointed to a pistol and ammunition it said was discovered on the man, identified as 37-year-old Alex Pretti, an ICU nurse at a VA hospital who the Minneapolis police chief said was licensed to carry a concealed weapon.

"This looks like a situation where an individual arrived at the scene to inflict maximum damage on individuals and to kill law enforcement," Homeland Security Secretary Kristi Noem told a news briefing, while White House deputy chief of staff Stephen Miller referred to Pretti as an "assassin".

However, bystander videos from the scene verified and reviewed by Reuters showed Pretti holding a phone in his hand, not a gun, as he tried to help other protesters pushed to the ground by immigration agents.

The shooting also raised tensions between state and federal officials, already at odds with the US administration over the shooting of Renee Good in Minneapolis on Jan 7.

In the shooting of Good, the administration also claimed that she had intended to harm federal agents, though cellphone footage of the incident raised questions about the federal government's description of the incident.

Last week, a report from the Hennepin county medical examiner listed Good's death as a homicide, which is defined as a person causing the death of another, though it does not mean a crime was committed.

President Donald Trump lashed out at Walz and the mayor of Minneapolis.

"Where are the local Police? Why weren't they allowed to protect ICE Officers?"

Trump said the governor and mayor "are inciting Insurrection, with their pompous, dangerous, and arrogant rhetoric."

Backed by a record $170 billion in funding for immigration agencies through September 2029, the crackdown has recently focused on Minneapolis, where about 3,000 federal agents have been deployed.

Former president Barack Obama called Pretti's death a "heartbreaking tragedy" and warned that "many of our core values as a nation are increasingly under assault."

AP reported that he urged the administration to work with city and state officials "to avert more chaos and achieve legitimate law enforcement goals".

"This has to stop," Obama said.

Chen Hong, director of the Asia Pacific Studies Center at East China Normal University in Shanghai, believes that sharply opposing narratives about law enforcement from different camps are likely to harden positions and intensify social tensions.

The standoff between the federal and state governments may spill over into Congress, he added.

"On Capitol Hill, issues such as immigration policy, homeland security funding, law enforcement authorizations and oversight hearings are likely to become flashpoints of intense partisan confrontation. This could escalate into a budgetary dispute, thereby heightening the risk of a federal government shutdown."

Li Haidong, a professor at China Foreign Affairs University, said that Minnesota, as a state long governed by Democrats, is known for its diverse and inclusive immigrant culture.

However, the Republican-led federal government's recent immigration crackdown is widely seen as an attempt to reshape the local voter base through mass deportations of illegal immigrants and even some legal residents.

These policies have severely disrupted Minnesota's long-established cultural ecosystem and social fabric, triggering widespread public discontent and deepening societal tensions, Li said.

As the midterm elections draw closer, immigration is set to become the main battleground in partisan politics.