Three African-Americans shot dead in Oklahoma

At least three African-Americans have been killed and two others injured in separate shootings in the US state of Oklahoma in what is perceived as a racially-motivated attack.

The shooting spree happened in north Tulsa, Oklahoma early Friday morning, AP reported.

All five victims were out walking when they were shot, homicide detective Sgt. Dave Walker said.

He added that police think the shootings are linked because they happened around the same time in the same general area.

Police do not believe the victims knew one another and are trying to determine the circumstances behind the killings.

The Tulsa Police Department named the victims as Dannaer Fields, 49, Bobby Clarke, 54, and 31-year-old William Allen.

Detectives are searching for a white pickup truck that a white male was driving around the area at the time of the shootings.

Meanwhile, Tulsa police spokesman Capt. Jonathan Brooks said investigators were looking into whether the shootings may have been possible hate crimes.

The murder of a young African-American in Florida brought to light the case of hate crimes in the US.

The unarmed 17-year-old Trayvon Martin was killed by neighborhood watchman George Zimmerman in February.

Zimmerman claimed that he had acted in self-defense, saying that the victim slammed his head into the pavement repeatedly before he fired the gunshot. He has not been charged with any crime.

Last month, the 22-year-old African-American Rekia Boyd was fatally shot by an off-duty Chicago police officer.

The issue of hate crimes is one of the most controversial topics in the Unites States, and has sparked several demonstrations across the country.