US police launch manhunt after three are killed in Tulsa

Federal authorities are helping Oklahoma police investigate the shootings of five African-Americans, three of whom were killed, within a few hours.

The police say there are searching for a white male in connection to the attacks.

Community leaders have tried to calm fears of further attacks.

The police said they were searching for a white man driving a white pick-up truck, who was seen in the area of three of the shootings.

Tulsa police chief Chuck Jordan said they were investigating whether the attacks were hate crimes, after investigators earlier said the incidents were linked.

The FBI has joined a task force set up to investigate the killings, he said.

Jack Henderson, a city councillor for the district where the attacks occurred, urged people to come forward with information.

"This is Tulsa, Oklahoma. We should have the ability to stand out on your porch anytime, day or night, that you want to, to walk down the street, day or night.

"And the only way that this person is going to be brought to justice is we need some leads."

A 49-year-old was the first killed at about 1:00am local time on Friday.

Minutes later the gunman approached two other men and asked for directions before shooting them. They survived but later two more were shot dead nearby.

Tulsa's police department has been tainted by accusations of corruption.

Three ex-police officers and a former federal agent were sentenced to prison in December after a two-year investigation involving allegations of falsified search warrants, nonexistent informants, perjury and stolen drugs and money.

Two other ex-officers were acquitted of stealing money during an FBI sting and fired after an internal affairs investigation.

More than a half-dozen lawsuits have been filed by people who claim they were wrongfully locked up by police, and nearly 40 people had their convictions overturned or prison sentences commuted as a result of the corruption probe.

Prosecutors have suggested the five police officers who were charged were part of a broader plot in which corrupt officers stole money and drugs, conducted illegal searches and fabricated evidence without fear of getting caught.