A 21-year-old man suspected of carrying out a shooting in Atlanta in which eight people were killed has denied a racial motive to the attacks that have shaken the country's Asian community, police said.

Six of the victims of last night's killings were of Asian origin, exacerbating concerns over a surge in violence targeting the community during the pandemic.

Authorities however stressed they had not determined the motive of the shooter, identified as Robert Aaron Long, a white man who is believed to have acted alone.

"The suspect did take responsibility for the shootings," Captain Jay Baker of the Cherokee County Sheriff's Office told a news conference.

"This is still early, but he does claim it was not racially motivated," Baker added. 

"He apparently has an issue, what he considers a sex addiction, and sees these locations as... a temptation for him that he wanted to eliminate."

Authorities arrested Mr Long after tracking his phone following a brief pursuit about 240km from Atlanta, officials said.

After he was detained, "he made a comment... that he was headed to Florida and that he was going to do similar acts in that state," Captain Baker said, adding that Mr Long wanted to target "some type of porn industry."

President Joe Biden said violence against Asian-Americans is "very troublesome."

"I know that Asian Americans are very concerned," Biden said, though he stressed any motive had "yet to be determined."

Democratic House Speaker Nancy Pelosi described the shootings as "a vicious and vile act that compound the fear and pain that Asian-Americans face each day."

Handout photo from Crisp County Sherriff's Office of Robert Aaron Long

The incident began with an attack at Young's Asian Massage in Acworth, an Atlanta suburb, where four of the victims were killed and a man was wounded.

Police said four women were subsequently killed in attacks on two neighboring spas in the northeast of Atlanta.

In the initial attack, the sheriff's department has charged Mr Long with four counts of murder and one count of aggravated assault, US media reported.

Officials did not immediately announce charges related to the attacks at the two spas.

Vice President Kamala Harris said the latest mass shootings spoke "to a larger issue which is violence in our country."

Cherokee County Sheriff Frank Reynolds said Acworth, a normally quiet commuter community, had experienced few murders and yesterday's violence was "a shock to all of us."

Adriana Mejia, niece of the wounded victim in the Acworth attack, said the family was "devastated" after her uncle was shot and that they were praying for his recovery.

"We never know when we're at the wrong place at the wrong time because this was so all of a sudden," she said.

South Korea's Yonhap News Agency reported the country's foreign ministry had confirmed that four of the victims were of Korean descent.

The shootings come as reports of attacks against Asian-Americans have spiked in recent months - fuelled during the Covid-19 pandemic, activists believe, by talk of the "Chinese virus" by former president Donald Trump and others.

"It shocks the conscience," Sam Park, a local representative of the Asian-American community, told AFP in Atlanta.

"We have lost so many lives this past year. We have seen racism and discrimination and a surge of violence against Asian-Americans who are scapegoated because of the pandemic."

Former president Barack Obama said on Twitter that while the shooter's motive was not yet clear, "the identity of the victims underscores an alarming rise in anti-Asian violence that must end."

In an address to the nation last Thursday Mr Biden condemned what he called "vicious hate crimes against Asian-Americans who have been attacked, harassed, blamed and scapegoated."

"It's wrong. It's un-American. And it must stop," he said.