Police arrested two 16-year-old youths on robbery charges yesterday and were looking for a third teen-ager allegedly the triggerman - in the shooting of a taxicab driver in Southeast last week.

The arrests are the first linked to the recent rash of holdups and assaults on taxicab drivers that have plagued hackers to the point where many no longer pick up young fares, particularly in remote areas of the city.

The two youths, arrested on information given by an informant, were charged in connection with the Sept. 14 shooting of William Jones, 37, a Capitol Cab driver who was shot in the head last week and is hospitalized in critical condition.

Jones was responding to a call for a cab at a housing project in the 2700 block of Stanton Road SE, police said. A teen-ager met him at the address and said he would summon the fare.The youth returned with three other young men, one of whom shot Jones at point-blank range without warning.

Police late yesterday broadcast a lookout for a 16-year-old who is believed to be the gunman in the Jones case. The youth, police said in their bulletin, "has been involved in numerous robberies and numerous arrests for the past four years." No one in the department could give an explanation as to why the youth was not now incarcerated.

At least 50 members of the police Special Operations Division, sent into Northeast and Southeast Tuesday in response to the taxicab holups, were searching for the suspected gunman last night. They were aided by a 10-man special detail of the police robbery squad.

Police said the suspect is known to carry a "large-caliber revolver" and should be considered "extremely dangerous."

Police sent the two other juveniles charged with robbery to the District Receiving Home in Northeast. A fourth juvenile suspect in the Jones shooting has not been identified, police said.

None of the youths go to school or work, according to police.

Meanwhile, another cabdriver was held up yesterday, the 10th such case this month.

Willie Menifee, 43, a driver for the Globe Cab Co., picked up a teen-ager at 1st Street and Martin Luther King Avenue SE shortly before 5 p.m. yesterday. Following the youth's instructions, he took him to the back of a house in the 700 block of Chesapeake Street SE, police said.

When he stopped his cab, Menifee said, the youth pulled a gun, announced a robbery, got $3 from the hacker and fled down an alley. Menifee was not injured.