The FBI along with the US Department of Justice (DoJ) has opened a civil rights investigation into the shooting of a Sikh man by a partially-masked gunman, who shouted "go back to your own country", the Press Trust of India (PTI) reported.

Deep Rai, a US national of Indian-origin, was shot outside his home in Kent, Washington, on Friday.

"The FBI's Seattle Field Office, in conjunction with the DOJ's Civil Rights Division, has opened a civil rights investigation into the March 3 shooting incident in Kent, Washington," Ayn Dietrich-Williams, spokesperson of FBI Seattle Field Office, told PTI.

The federal investigation is in addition to a criminal investigation being conducted by the Kent police. The FBI is investigating the incident as a hate crime.

"The FBI is working with the Kent Police Department and will collect all available facts and evidence to determine if there is a federal civil rights violation. As this is an ongoing investigation we are not able to comment further at this time," she said.

The FBI defines a hate crime as a "criminal offense against a person or property motivated in whole or in part by an offender's bias against a race, religion, disability, sexual orientation, ethnicity, gender, or gender identity", according to the bureau's website.

Rai was released from the hospital on Sunday.

Police Chief Ken Thomas said detectives have canvassed Kent's East Hill neighbourhood, where the shooting took place, and have spoken with potential witnesses and area businesses.

However, he declined to discuss any evidence detectives collected.

Governor Jay Inslee, in a statement, condemned the shooting, saying "these acts of violence are hateful, detestable, and un-American". -- Bernama