“Two people are in the hospital following a shooting involving federal agents,” Portland Police said in a statement.

“Their conditions are unknown.”

An affiliate of the US ABC News network reported that agents involved in the shooting were US Customs and Border Protection agents and that the FBI was leading the probe into the incident.

Portland Police said in the statement that local officers were not involved.

“Officers have determined the two people were injured in the shooting involving federal agents,” the statement said.

Portland Police Chief Bob Day acknowledged 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,” he said.