Liane Carrascoso was headed to pick up her 5-year-old son at Harriet Tubman Elementary School in Columbia Heights on Friday when she saw police officers urgently closing down nearby streets.

Two men had been shot less than 400 feet from the school’s front door, and officers were searching for three possible shooters. Classes had ended about an hour earlier, but children still mingled on the playground in an aftercare program, waiting to be picked up.

Carrascoso said teachers told her that one of the shooters had run right by the playground. “I saw his teachers, and they looked worried,” she said. “They told me the kids were vulnerable at that moment.”

There was more gunfire in the blocks near the school over the weekend, all within a short radius of the Columbia Heights Metro station in Northwest Washington. On Sunday, a man was shot inside an apartment building, which hours later caught fire, and another man was shot before noon at Harvard and 14th streets. Police said they were investigating whether any or all of the incidents, including the fire, were related.

“Unhinged, off-the-hook violence,” said Kent Boese, who chairs the Advisory Neighborhood Commission for an area that includes Columbia Heights. “I think their proximity, with so much of them concentrated in one area and in such a short period of time, I would not be surprised if they were connected in some way.”

The community leader pressed authorities for every resource available. “We need this to be a coordinated and collaborative approach,” Boese said. “Clearly we’re not there right now if we have this level of violence.”

Even before the weekend, it had already been a violent year in Columbia Heights, with eight other shootings, two of them fatal.

D.C. Council member Brianne K. Nadeau (D-Ward 1) said she learned from authorities that “not all [the shootings] are related, but some of them are.” She attributed some to rival street crews and said the city had sent in violence interrupters, who immerse themselves in neighborhood conflicts to prevent future incidents.

“Part of this is related to a dispute,” Nadeau said. “Ending that dispute is the key to ending the majority of the violence we have seen.”

Cmdr. Stuart Emerman, who runs the 3rd District, emailed one parent of a Tubman student and listed a litany of recent firearms seizures in the area. He said police found a juvenile with a loaded .40-caliber handgun in March and three other people, each with guns, in April. “We share in your concerns regarding the recent incidents in gun violence in our community,” the commander wrote.

Emerman, who confirmed that he sent the email, wrote that he has increased police presence so much that “there has been the case where officers were patrolling nearby on several of these instances and actually heard the gunfire.”

Other city agencies have sent additional resources as well.

Police have made arrests in Columbia Heights’ two homicides this year. One suspect was 15 years old. The other told police he shot a rival crew member because the man had previously fired at him, according to the arrest affidavit filed in the case.

In another incident this year, one man was wounded in an apartment stairwell in a shooting that police said was sparked by a $15 marijuana deal.

Police said they were working hard to learn motives and make arrests in the shootings that occurred this weekend.

Capt. Ralph McLean wrote on the department’s Internet community bulletin board that the man shot inside the Tivoli apartment building early Sunday on Hiatt Place has refused to cooperate with detectives, and no arrest has been made.

But McLean said that investigators have identified three suspects in Friday’s shooting near Tubman Elementary and that arrest warrants were being issued. He said police recovered a discarded gun and a vehicle stolen from Maryland that is believed to have been used by the shooters.

Carrascoso, the Tubman parent, said she arrived at the school just before teachers rushed the children inside and put the school on lockdown, the third time this year because of gunfire.

She said her kindergartner doesn’t yet understand the commotion and worry. “He’s lived his whole life in Columbia Heights,” she said. “It’s gotten worse in the past couple months, but it’s not new to us.”