An argument between two women might have sparked a shooting Monday that led to a murder charge for a Chester man, who police said remained at large yesterday.

Witnesses identified Angus Richardson, 24, as the person accused of shooting and killing Otis Bullock, 21, and critically wounding his brother Leon, 19, police said. Both Bullocks lived in Chester.

Police said an arrest warrant was out for Richardson, who has been charged with murder, attempted murder, aggravated assault, terroristic threats, and weapons and related charges, according to court papers.

There is also an active arrest warrant on file for Richardson in connection with a domestic incident from November, police said.

Monday, police were called to the 2600 block of McCarey Street just after 3:30 p.m. for a report of a shooting.

They found two wounded victims on the ground.

Otis Bullock was pronounced dead at 6:01 p.m. at Crozer-Chester Medical Center. Yesterday, Leon Bullock was listed in stable condition after surgery. Police said he was expected to survive.

A witness said a man known as Gus opened fire from the passenger-side window of a white SUV. Police said Gus was later identified as Richardson.

G. Michael Green, Delaware County district attorney, said Richardson had previously threatened the witness.

Authorities say they believe the threats stemmed from an argument between the witness and Richardson's girlfriend. The Bullocks and others went to the area of West 21st Street to face Richardson over the threats, and a "physical confrontation" developed, Green said.

The shooting occurred after the Bullocks and the others returned to McCarey Street.

Green said the driver of the white SUV was a "person of interest" in the case. Green said he thought Richardson was still in the area.

Police are asking anyone with information to call Chester detectives at 610-447-8430 or the Chester City Anonymous Tip Line at 610-447-7810.

Contact staff writer Mari A. Schaefer at 610-892-9149 or mschaefer@phillynews.com.