LANCASTER (June 22, 2010)--A communitywide prayer vigil is scheduled for Wednesday in Lancaster for Police Officer Craig Shaw, a father of two who was shot to death Sunday night after responding to a report of gunfire at an apartment complex.

Investigators believe David Brown, Jr., 27, the son of Dallas Police Chief David Brown, Sr., shot Shaw, 37, to death before he was killed in an exchange of gunfire with officers.

Earlier, investigators say, Brown evidently shot Jeremy McMillan, 23, who was pulling into the complex in his car in which his girlfriend and two small children were also riding.

That shooting appears to have been random.

A Lancaster ministerial group is organizing the Wednesday morning prayer vigil for Shaw.

A candlelight vigil is scheduled Thursday night at Lancaster's police headquarters, and Shaw's funeral is for Saturday morning at a south Dallas church

A statement released Sunday said Brown was mourning the loss of his son and of the slain officer.

In a statement to his officers Tuesday, Brown acknowledged that the past few days have been "troubling and emotional."

He offered condolences to the families of the two men his son killed.

"My family has not only lost a son, but a fellow police officer and a private citizen lost their lives at the hands of our son."

"That hurts so deeply I cannot adequately express the sadness I feel inside my heart."

Brown's son had a minor criminal record.

He pleaded no contest to misdemeanor delivery of marijuana in 2004 after he was charged originally with a felony.

Even before the shootings, the elder Brown knew tragic loss well.

In 1988, his former police partner and academy classmate Walter Williams was shot to death in the line of duty.

Drug dealers in Arizona killed his younger brother, Kelvin Brown, three years later.