A man accused of stabbing two people blocks away from the U.S. Capitol Building had his probation for a previous domestic violence conviction revoked about a week before the attacks, according to court records.

Jerome Swinson, 39, of southeast Washington, was arrested Tuesday. Police and witnesses said Swinson approached an elderly man who was sitting in a chair at an Exxon station at Pennsylvania Avenue and 4th Street SE and stabbed him in the neck.

Employees of the gas station helped the victim and chased the attacker. One employee followed the attacker in his car while calling police. But as the suspect fled, he encountered another man and stabbed him, police said.

Swinson was on probation after being convicted for a domestic violence incident that happened in 2014, according to court records.

Swinson's probation was declared "terminated/unsuccessful" on Sept. 6 after he failed to show up for eight court-ordered drug tests.

It is unclear if the D.C. probation office, a federal agency, would have to notify D.C. police that Swinson had violated probation.

"My children go to school close by. I mean, it's a tight-knit community over here and just... an unprovoked stabbing - hearing something like that - it's just jarring and shocking," said Advisory Neighborhood Commissioner Jennifer Samolyk who lives in the area of the stabbings.

Samolyk said she and other residents were frustrated to learn Swinson had is probation revoked.

According to law enforcement sources, Swinson was also stopped a couple of times over the weekend for behaving erratically, but police had no basis to arrest him. Officers would not have had access to the information about his probation, the sources said.