A Prince George's County judge substantially reduced bail yesterday for two suspects charged with throwing rocks at motorists on the Capital Beltway and critically injuring a teenage girl. The judge said he did not believe the young men would pose a threat to society if released.

District Court Judge Silvania Woods set bail at $25,000 for the two suspects, Maurice Edward Ford, of Oxon Hill, and John Lavin Burgess, of Forest Heights. The men, both 18, had each been jailed in lieu of $150,000 bail.

Neither suspect had posted the reduced bail by last night, and both remained in the Prince George's County Correctional Center. The two were arrested Saturday and charged with one count each of assault with intent to murder in the May 27 stone-throwing incident.

Woods ordered that Ford and Burgess, if they are able to post bail, submit to electronic home monitoring pending their trials. Neither would be allowed to leave his home except to work or attend school or church.

A 17-year-old youth charged as a juvenile in the incident is still in custody. A hearing on a move to try him as an adult is scheduled for next month.

Police said 27 vehicles were struck with stones on the Beltway near Livingston Road in Oxon Hill about 2:30 a.m. May 27. Destiny Morris, 15, of Hagerstown, Md., was critically injured and remained comatose yesterday.