District police have obtained arrest warrants charging two half brothers held in the Prince George's County jail with one of several holdups of D.C. self-service gas stations where the threat of fire by gasoline was used to demand money.

Police have begun extradition proceedings for Theodore Shipes, 28, of 7226 Landover Rd., Landover, and John C. Marable, 29, of 236 Nicholson St. NE., who are being held in the Prince George's County Detention Center in lieu of $15,000 bond.

D.C. police are investigating the robbery of four Northwest filling stations in the last two weeks and the attempted holdup of three stations.

In most of the holdups, a robber would splash gasoline near the cashier's booth, light a match and demand money. In one of the incidents, an attendant was injured as she escaped from the flames after the robber lit a match and ignited gasoline he had poured on the cashier's booth.

All seven of the D.C. robberies or attempts, which began May 23, occurred between midnight and 6 a.m. at stations where a woman was inside the cashier's booth alone, according to Capt. William White III, a police spokesman.

Cpl. Bruce Gentile, a Prince George's police spokesman, said Shipes and Marable were arrested Sunday and charged with attempted robbery with a deadly weapon of a convenience store in the 6300 block of New Hampshire Avenue. The two were later charged with the robbery last Friday of the Food Barn grocery at 5819 Eastern Ave.

Prince George's detectives are trying to determine if the two men are linked to three other robberies, including the holdup of a gas station, Gentile said.

Shipes and Marable are charged in the D.C. Superior Court arrest warrant with armed robbery in the May 28 robbery of an Amoco service station at 6300 Georgia Ave. NW.