As States sent Union regiments south, on April 19, Baltimore mobs in control of the rail links attacked Union troops who were changing trains. Local leaders' groups later burned critical rail bridges to the capital and the Army responded by arresting local Maryland officials. Lincoln suspended the writ of habeas corpus where needed for the security of troops trying to reach Washington. John Merryman, one Maryland official hindering the U.S. troop movements, petitioned Supreme Court Chief Justice Roger B. Taney to issue a writ of habeas corpus. In June Taney, ruling only for the lower circuit court in ex parte Merryman, issued the writ which he felt could only be suspended by Congress. Lincoln persisted with the policy of suspension in select areas.
Michael Vigna, a competitive bike rider hassled about 9:05 p.m. by the group, one of whom tried to punch him. Antonio Diaz, a 52-year-old man walking in the park near 105th Street, was knocked to the ground by teenagers about 9:15 p.m., who stole his bag of food and bottle of beer. He was left unconscious but soon found by a policeman. Gerald Malone and Patricia Dean, riding on a tandem bike, were attacked on East Drive south of 102nd Street about 9:15 p.m. by boys who tried to stop them and grab Dean; the couple called police after reaching a call box.
David Lewis, the banker, attacked and robbed about 9:25–9:40 Robert Garner, attacked about 9:30 p.m. David Good, attacked about 9:47 p.m. John Loughlin, the 40-year-old teacher, severely beaten and kicked about 9:40–9:50 p.m. near the reservoir and left unconscious. He was also robbed of a Walkman and other items.
At 9 p.m. on April 19, 1989, a group of an estimated 30 – 32 teenagers who lived in East Harlem entered Manhattan's Central Park at an entrance in Harlem, near Central Park North. Some of the group committed several attacks, assaults, and robberies against persons walking, biking, or jogging in the northernmost part of the park and near the reservoir, and victims began to report the incidents to police. Within the North Woods, between 105th and 102nd streets, they were reported as attacking several bicyclists, hurling rocks at a cab, and attacking a pedestrian, whom they robbed of his food and beer, and left unconscious. The teenagers roamed south along the park's East Drive and the 97th Street transverse, between 9 and 10 p.m.
At least some of the group traveled further south to the area around the reservoir, where four men jogging were attacked by several youths. Among the victims was John Loughlin, a 40-year-old schoolteacher, who was severely beaten and robbed between 9:40 and 9:50. He was hit in the head with a pipe and stick, knocking him briefly unconscious. At a pre-trial hearing in October 1989, a police officer testified that when Loughlin was found, he was bleeding so badly that he "looked like he was dunked in a bucket of blood".