A 20-year-old Southeast Washington man told police yesterday that he and a second man had planned to shoot and rob two undercover D.C. police officers who they believed were trying to buy PCP from them Wednesday night, court documents filed yesterday said.

Herbert Austin of 2912 Second St. SE was charged yesterday with assault with intent to kill a police officer.

The court documents filed by police assert that he and another man, who remains at large, approached two undercover officers during a drug purchase at an Exxon gas station at 3900 Martin Luther King Jr. Ave. SW Wednesday night and began firing at the officers.

As backup officers approached to help, a small gun battle ensued and a third officer was shot before Austin was arrested and the other man fled, police said.

Police are seeking a third suspect who investigators believe was involved in the drug purchase, though not involved in the shooting.

The most seriously injured of the three officers, Troy Pumphrey, 25, was in serious but stable condition at Hadley Memorial Hospital. The other two, less seriously wounded officers, Gerald Awkard, 40, and Richard Watkins, 36, were taken to Greater Southeast Community Hospital.