D.C. police officials said yesterday they were worried that a weekend of shootings in Columbia Heights may reflect a renewal of drug activity in a neighborhood that has recently struggled to overcome violence and revive its streets.

Two people were killed and two were injured in shootings there late Saturday and early Sunday. Assistant Police Chief Ronald C. Monroe said yesterday that the 4th District plans to step up foot patrols in Columbia Heights and conduct "a couple of tactical operations" to target criminal activity.

One of the six police "open-air mini-substations" may be placed in the area, Monroe said. The mini-substations, to be staffed 24 hours a day, are planned for the city's most violence-ridden communities.

Altogether, four people were shot to death and five were wounded in five incidents over the weekend in Southeast Washington and Columbia Heights, and on the border between Southeast and Prince George's County. The shootings were particularly distressing to Columbia Heights, which recently had a more hopeful outlook.

With a Metro station scheduled to open in September, some of the nation's most prominent developers have been competing to invest as much as $135 million to transform the neighborhood into a thriving urban center with movie theaters, shopping and restaurants.

Smaller efforts by neighborhood residents, such as a team from All Souls Church cleaning up the drug-infested Girard Street playground, also have boosted the area's collective confidence.

The shooting in the 1400 block of Monroe Street early Sunday, which killed one woman and injured two men, resulted from a petty dispute, said 4th District Cmdr. Melvin Scott.

In another incident, about 10:45 p.m. Saturday, a 24-year-old man was fatally shot in the 1300 block of Columbia Road, police said.

The recent shootings made longtime residents such as Carol Davis nostalgic for the days when violence in Columbia Heights meant muggings, breaking and entering, and big boys kicking little boys off bicycles.

"This is worse than 1968," said Davis, referring to the riots when nearly 300 businesses were burned out or looted. "I don't ever remember being afraid for my children or other children's lives back then. That you would walk down the streets and have that kind of violence now is something you feel."

Even near All Souls Church, John DeTaeye, interim associate minister, said the violence is palpable.

On a Friday afternoon about three months ago, residents and church members were renovating the Girard Street playground, a nighttime hangout plagued by gunfire and clouds of marijuana smoke. A young man asked if he could help out. Two days later, he was shot and killed on the playground he had tried to clean up.

All the violence has prompted DeTaeye and other community leaders to speak to the mayor about holding a day-long youth conference.

Mai Fernandez, deputy director of programs at the Latin American Youth Center, said violence is so out of control that she is asking for the mayor to place a police officer at the center permanently. Four bystanders were shot there two months ago when a gun battle broke out between feuding gangs after a party, police have said.

The Latin American Youth Center also hopes to obtain funding from the U.S. Justice Department's Weed and Seed initiative, which gives a grant of about $250,000 for increased law enforcement and job, parenting and youth programs.

"We are trying to deal with the issue that these kids are joining gangs because they don't know what the alternatives are," Fernandez said. "We are trying to have a more open dialogue about what the consequences are for perpetrating this kind of violence in the very neighborhoods and streets where they live."

Detectives were investigating a third shooting incident, in Southeast, in which a 29-year-old man was slain and a 20-year-old man standing next to him was shot in the left leg and foot. Sixth District Cmdr. Rodney D. Monroe said he believes the shootings were gang- and drug-related.

Police said they were closing in on a suspect in a fourth shooting, which injured two men on Stanton Road SE.

Prince George's County police said they are still investigating the shooting of Southeast resident Jerome Woodard, who was found lying in a parking lot in the 4100 block of Southern Avenue in Capitol Heights.

Top D.C. police officials sought to emphasize the District's overall drop in violent crime.

"This isn't by any stretch of the imagination one of the most violent periods in D.C. history, although it is something I am very, very concerned about," said Police Chief Charles H. Ramsey.

He and other police officials spoke at a news conference announcing a program in which police give 7-Eleven coupons to children who are seen doing good deeds.