A 30-year-old man was fatally stabbed Thursday morning during an altercation at a Center City subway station and police arrested a suspect about an hour later.

The slaying occurred on the first full day of a strike by SEPTA Transit Police officers.

Philadelphia police said the victim, whom they did identify, was stabbed once in his chest about 6:45 a.m. on the concourse at the Broad Street Line’s Walnut-Locust station. He apparently then made his way to the station’s Spruce Street entrance.

Medics took the man to Hahnemann University Hospital, where he was pronounced dead at 7:49 a.m.

SEPTA police supervisors, who are filling in for the striking officers, arrested a suspect an hour later, the agency said.

“The preliminary investigation indicates that this was not a random attack,” SEPTA said in a statement. “The individuals involved knew each other and were involved in an altercation that escalated to the stabbing.”

Philadelphia Homicide Capt. Jason Smith said surveillance video captured a “violent confrontation” between the men. Smith said the assailant, whose name was not immediately released, was taken into custody after apparently seeking help for his injuries at the Hub of Hope, a service center for the homeless in Suburban Station. He was hospitalized but not immediately charged, Smith said. .

The attack occurred amid a strike by SEPTA’s 178 police officers, which began Wednesday over a contract dispute regarding work rules.

The transit agency said it did not anticipate the strike would cause any service interruptions and that SEPTA intends to rely on the department’s 49 supervisors to work 12-hour shifts to cover patrols. Philadelphia police will assist with enforcement at transit hubs in the city, while police in suburban communities will provide coverage at Regional Rail stations.