One of the suspects had used Facebook to post an expression of grief and anger over his father's killing two years before.

TULSA, Okla. — Late Thursday afternoon, Jacob C. England, 19, posted a message on his Facebook page, expressing grief — and anger — over the second anniversary of his father’s death. England’s father, Carl, was shot on April 5, 2010, at an apartment complex here, and the man who was a person of interest in the case, Pernell Jefferson, is serving time at an Oklahoma state prison.

England is a Native American who has also described himself as white. Jefferson is black.

“Today is two years that my dad has been gone,” England wrote, and then used a racial epithet to describe Jefferson. “It’s hard not to go off between that and sheran I’m gone in the head,” he added, referring to the recent suicide of his 24-year-old fiancée, Sheran Hart Wilde. “RIP. Dad and sheran I Love and miss u I think about both of u every second of the day.”

Hours later, the authorities say, England and his friend and roommate, Alvin Watts, 32, waged what city leaders believe was a racially motivated shooting rampage in the predominantly black neighborhoods of north Tulsa early Friday, driving through the streets in a pickup and randomly shooting pedestrians. Three black people were killed, and two others were wounded in the attacks.

Unlimited Digital Access. $1 for 4 weeks.

England and Watts, who is white, were arrested early Sunday after investigators received tips to the state’s anonymous Crime Stoppers line, the authorities said. They will face three counts of first-degree murder, they said, and two counts of shooting with the intent to kill.

At a news conference in downtown Tulsa on Sunday, police officials said it was too early in the investigation to say precisely what motivated England and Watts, and they stopped short of describing the shootings as hate crimes.

“You can look at the facts of the case and certainly come up with what would appear to be a logical theory, but we’re going to let the evidence take us where we want to go,” said the Tulsa police chief, Chuck Jordan.

In Tulsa — a city of 392,000, about 62,000 of whom are black — the shootings shocked, frightened and angered many black residents on Easter weekend and prompted an intense manhunt. The authorities formed a task force called Operation Random Shooter, made up of more than two dozen local, state and federal investigators from the Tulsa Police Department, the Tulsa County Sheriff’s Office and the federal Marshals Service. The FBI also joined the investigation.

Jack Henderson, a city councilman who is black and whose district includes all of the shooting sites, said that before the arrests, many in the area were terrified.

“A lot of people in my community have been calling me, afraid that they couldn’t go outside, didn’t know if they could even go to church, didn’t know if they could go to the grocery store,” Henderson said at the news conference.

Henderson said he had heard from constituents that in one of the shootings, the suspects had approached their victims at random and asked for directions. “When they turned around to walk away, they just opened fire,” Henderson said.

In 1921, Tulsa was the scene of a riot that is one of the deadliest episodes of racial violence in the nation’s history, in which a mob of white Tulsans destroyed a black neighborhood and killed dozens, perhaps hundreds, of black residents.

Jordan declined to say if the suspects were cooperating with investigators, and he said that England’s Facebook postings would be part of the prosecution of the case.

England, a stocky young man with a mohawk-style haircut, graduated in 2009 from Sperry High School. Late Friday evening, hours after the first shooting, England suggested on his Facebook page that he was contemplating suicide because people were accusing him of unspecified acts that “I didn’t do,” he wrote, adding that it might be time to “call it quits.”

He wrote: “I hate to say it like that but I’m done if something does happen tonite be ready for another funeral later.”

In the series of comments that followed, his friends tried to comfort him, with some writing that they loved him. Others appealed to him to remember his sister, Cady, and his infant son, Jacob C. England II. “Please dont do anything stupid jake,” one friend responded. “Think about cady and the baby and everyone that loves you.” By midafternoon Sunday, both suspects’ Facebook profiles were no longer available.