Four persons were fatally shot in the District, including a 15-year-old junior high school student and a would-be robber, in four incidents in less than 24 hours.

No arrest has been made in any of the shootings, three of which were in different areas of Northwest Washington, police said.

In the latest incident about 4:30 p.m. yesterday, Byron A. Grey, 38, of 507 Decatur St. NW was shot while standing at Fifth and Crittenden streets NW, police said.

Grey was taken to the Washington Hospital Center Medstar unit, where he was pronounced dead about 5 p.m.

Also yesterday, Thomas Popp, 25, of 14952 London La. in Bowie was found about 2 a.m. outside 1462 Chapin St. NW with a gunshot wound in the chest. Popp was taken to the Medstar unit, where he died an hour later.

On Sunday, James Terry Walker, 29, of 2511 Savannah St. SE was shot by the resident of a house at 1625 E St. NE when he was discovered trying to break into the rear of the house about 8 p.m., D.C. police said.

Walker was taken to D.C. General Hospital, where he died about 10:30 p.m. Police refused to identify the resident who fired the shot. They said no charges had been filed but that a grand jury would investigate.

Police said they believe that a man who fled after Walker was shot may have been involved in the attempted burglary.

Also on Sunday, about two hours later, Ernest Lee Smith, a ninth grader at Shaw Junior High School in Northwest, was shot in the chest and left leg while standing in an alley in the 600 block of S Street NW.

Smith, who lives with his mother and younger sister and brother at 1309 Ninth St. NW, was found after neighbors reported hearing gunshots. William Tucker, who lives in a house near the alley, said he was in bed when he was roused by the sound of gunfire.

"I jumped up and looked out the window. I saw the fellow fall. It looked like he was dead when he fell," Tucker said.

Smith was taken to Children's Hospital, where he died about 11 p.m. Police said some evidence suggests that the killing was drug related or occurred during a robbery, but they declined to give details.

Lisa Jones, who also lives on Ninth Street, said her neighbor, who was better known by the nickname "Patrick," was well liked even though he had lived in the area for a short time.

"He always looked very playful, like he was happy and he didn't have much to worry about," she said.

Homicide investigators said the shootings bring the number of reported homicides in the city to 136 this year, compared with 161 for the same period last year. The number of cases that remain unsolved this year is 44, compared with 38 last year, an investigator said.