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

Witnesses identified Angus Richardson, 24, as the person who allegedly shot and killed Otis Bullock, 21, and critically wounded his brother Leon, 19, police said. Both Bullocks were Chester residents.

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

Police say there is also an active arrest warrant on file for Richardson in connection with a domestic incident from November.

Yesterday, 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. Today, Leon Bullock was listed in stable condition after surgery. Police say he is 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 believe the threats stem from an argument between the witness and Richardson's girlfriend. The Bullocks, along with others, went to the area of West 21st Street to face Richardson over the threats. 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 is considered a "person of interest" in the case. Green says he thinks Richardson is 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.