(CNN) -- Three people were killed and two were injured Friday in four shootings in north Tulsa, Oklahoma and police are searching for a lone suspected gunman, they said.
Tulsa police spokesman Capt. Jonathan Brooks said investigators were looking into whether the shootings may have been possible hate crimes.
"We're not absolutely certain, but a hate crime is a possibility. And we'll go with where the investigation leads us," he said.
All of the victims are black. The suspected shooter is a white male and is believed to be traveling in a white truck, said Brooks.
It was not immediately clear whether any of the victims knew each other, he said.
They range in age from 31 to 54. They were shot over the course of seven hours at four different street locations in the early morning, Brooks said.
Tulsa police formed a joint task force with the local FBI office as well as the U.S. Marshals Service. In the event the shootings turn out to be hate crimes, "they can help us pursue it," he said.
"This is not your standard homicide," said Brooks.