By Therese Apel

HATTIESBURG, Miss. (Reuters) - A vigil to honor two police officers shot to death in Hattiesburg, Mississippi, drew law enforcement officers from across the state on Monday, while four suspects appeared in court.

Marvin Banks, 29, was charged with two counts of capital murder after the two police officers were gunned down on Saturday during a routine traffic stop, officials said. Banks was denied bond as he already faces grand larceny and weapons charges in an unrelated case.

His brother, Curtis Banks, 26, and Joanie Calloway, 22, were charged with accessory after the fact of capital murder and a fourth person, Cornelius Clark, was charged with obstruction of justice.

The shooting, which was the first killing of a Hattiesburg police officer in more than 30 years, shook the southern Mississippi city of 48,000 people. Mayor Johnny DuPree said information provided by the community was key to the swift arrests.

Officers Benjamin Deen, 34, and Liquori Tate, 25, a recent police academy graduate, were shot Saturday after Deen stopped a gold Cadillac Escalade. Autopsy results by the Mississippi Bureau of Investigations released on Monday showed one of the officers was shot in the face and the other in the back.

At least one of the suspects fled in a police car that was later found abandoned. Officials have declined to discuss a possible motive.

State court records show the Banks brothers are felons with multiple firearms-related arrests.

Calloway had been driving the Escalade at the time of the shooting, DuPree said.

At the vigil, fellow officers recalled Deen, a married father of two and Hattiesburg officer of the year in 2012, as a "country boy" who once saved a family from a burning building.

Tate was described as a enthusiastic officer who loved the sound of the police siren.

Deen and Tate are the ninth and 10th law enforcement officers in the United States shot and killed by assailants in 2015, according to the Officer Down Memorial Page, a non-profit organization that tracks police deaths in the line of duty.

U.S. Attorney General Loretta Lynch said the Justice Department stood ready to assist with the investigation into the "devastating" killings.

(Writing by Jonathan Kaminsky and David Adams; Editing by Colleen Jenkins, Doina Chiacu and Bill Trott)