BALTIMORE (AP) _ Two juveniles were arrested Saturday and charged as adults in connection with a bombing that critically injured the father of a police officer.

Frank Busnuk, 73, father of Capt. Gerard F. Busnuk, was in critical condition at the Maryland Shock Trauma Center after seven hours of surgery, nursing coordinator Therese Trainu said.

His left arm had to be amputated below the elbow and his right arm was severely injured, as were his face and upper torso, when a package he found on the roof of his son's car exploded as he examined it Friday.

Police believe the bomb, apparently rigged to detonate when it was picked up, was meant for the younger Busnuk, who had filed complaints about vandalism in his neighborhood.

The explosion was heard five blocks away, said Fire Capt. Stephen Fugate said. ''Whoever made that bomb knew what they were doing.''

The juveniles, ages 16 and 17, were charged with attempted murder, reckless endangerment and explosives violations, said Jim Yurgealitis, spokesman for the federal Bureau of Alcohol, Tobacco and Firearms.