A US immigration agent has shot and wounded a man and a woman in Portland, Oregon, authorities said, leading local officials to call for calm given public outrage over the agency's shooting death of a Minnesota woman a day earlier.

"We understand the heightened emotion and tension many are feeling in the wake of the shooting in Minneapolis, but I am asking the community to remain calm as we work to learn more," Portland police chief Bob Day said in a statement.

The Portland shooting unfolded on Thursday afternoon as US Border Patrol agents were conducting a targeted vehicle stop, the ⁠Department of Homeland Security (DHS) said in a statement.

It said the driver, a suspected Venezuelan gang member, attempted to "weaponise" his ‍vehicle and run over the agents.

In response, DHS said, "an agent fired a defensive shot" and the driver and a passenger drove away.

Portland police said that the shooting took place near a medical clinic in eastern Portland.

Six minutes after arriving at the scene and determining federal agents were involved in the shooting, police were informed that two people with gunshot wounds – a man and a woman – were asking for help at a location about three kilometres to the northeast of the medical clinic.

Police said they applied tourniquets to the man and woman, who were taken to a hospital.

Their condition was unknown.

The shooting came just a day after a federal agent from US Immigration and Customs Enforcement (ICE), a separate agency within the Department of Homeland Security, fatally shot a 37-year-old mother of three in her car in Minneapolis.

Police said the probe into the Portland shooting was being led by the FBI, just like with the Minneapolis killing.

That shooting has prompted ⁠two days of protests in Minneapolis.

Officers from both ICE and Border Patrol have been deployed in cities across the United States as part of US President Donald Trump's immigration crackdown.

While the aggressive enforcement operations have been cheered by the president's supporters, Democrats and civil rights activists have decried the posture as an unnecessary provocation.

Officials contend criminal suspects and anti-Trump activists have increasingly used their cars as weapons, though video evidence has sometimes contradicted their claims.

Portland mayor Keith Wilson said his city was now grappling with violence at the hands of federal agents and that "we cannot sit by while constitutional protections erode and bloodshed mounts."

He called on ICE to halt all its operations in the city until an investigation could be completed.

"Federal militarisation undermines effective, community-based public safety, and it runs counter to the values that define our region," Wilson said.

"I will use every legal and legislative tool available to ⁠protect our residents' civil and human rights." (Reuters)