A police force of 150 hastily assigned officers patrolled the streets here today and civil rights officials began investigating weekend rioting that left two men and a teen-ager dead and four others wounded.

The disturbances were sparked by the fatal shooting of a 15-year-old black near the parking lot of a private all-white night club, police said. An unidentified black man and a white former policeman wre killed in subsequent clashes between police and nearly 200 blacks.

"This is a situation which we didn't think would ever happen in Idabel," said Mayor Rex Helms. "But it did and now we don't really know what to expect."

Helms said most black residents of the southeast Oklahoma town of 6,000 remained home today and a tense mood prevailed. The town's population is about 20 percent black.

While many downtown businesses remained closed for the day, some merchants armed themselves with rifles before opening their doors.

The trouble began about 4 p.m. Sunday when a crowd of about 100 blacks converged on City Hall, claiming police were not pursuing an investigation into the slaying of Henry Lee Johnson, 15, whose body was found that morning near the Black Hat Club, a mostly white night club on the fringes of a black neighborhood. The club has been the scene of previous racial incidents.

Assistant District Attorney Al Cecil said today that he had filed a first-degree murder charge against Walter Anthony DeShazo, 29, of Horatio, Ark., in connection with Johnson's death.

Cecil also said that, contrary to earlier reports, Johnson has been shot to death, not beaten.

Eight blacks were jailed today in connection with the gunfire and vandalism.

Auxiliary police officer Ruben Farmer, 36, an Idabel service station owner, was fatally wounded in an exchange of gunfire about 10:15 p.m. Sunday. He died en route to a Texarkana, Tex., hospital.

It was not until daylight today that officers found the body of William Mack Jr., 26, a black, in a weedy area behind a self-service gasoline station that had been vandalized the night before.

Highway Patrol Trooper Harry Tunnel, 38, a driver's license examiner, was wounded in the face by ricocheting buckshot. Three black men also were wounded.