A police standoff in Randallstown, Md., on Monday in which a 23-year-old woman with a shotgun was killed after the police say she had been encouraged by her online followers to defy their orders has highlighted an unexpected role of social media in violent encounters.

During the standoff, which lasted several hours, videos from inside the apartment were posted to the Instagram account of the woman, Korryn Gaines, 23, whose 5-year-old son was also in the home, according to the Baltimore County Police Department.

The police said Ms. Gaines had repeatedly pointed her shotgun at officers, at least once while her son was in her arms. At one point, she said she would kill the officers if they did not leave, the police said. She was killed in an exchange of gunfire with officers. Her son was wounded. It is not known if he was hit by the police or by fire from his mother’s shotgun, the New York Times reports.