An armed robbery suspect was arrested early yesterday on the grounds of the Vice President's House at Observatory Circle after two men scaled a fence surrounding the compound in an apparent effort to elude police, officials said.

Both Vice President George Bush and Barbara Bush were home and were notified when police began searching for the men about 1:15 a.m., a Secret Service spokeswoman said. She said D.C. police captured the suspect in the compound "about the farthest point" from the residence and that the family was never in danger.

D.C. police said the man was arrested after a police dog found him in a wooded area in the southwest part of the estate near Wisconsin Avenue NW. They said Ronald Cole Porter, 29, was taken to D.C. General Hospital where he was treated for dog bites and subsequently was charged with armed robbery in a holdup on Wisconsin Avenue that occurred shortly before the search of the estate. Porter, whose address was not immediately available, was being held without bond last night at the D.C. Jail.

A second robbery suspect who police believe scaled the 8-foot iron fence that surrounds the U.S. Naval Observatory and the Vice President's House, escaped, police said. Scores of police officers and Secret Service agents, aided by dogs and a helicopter, took part in the 90-minute search of the compound, which ended about 2:45 a.m., officials said.

D.C. police Lt. James R. Waybright said the incident started about 1:10 a.m. in the 1200 block of Wisconsin Avenue NW when two gunmen, apparently aided by a lookout, robbed two men as they were getting into a taxi. The robbers then ran north on Wisconsin Avenue and west on Prospect Street NW.

The victims hailed a police cruiser and gave a description of the gunmen, Waybright said. A short time later, he said, Sgt. Roy Brown spotted a car speeding in reverse on Prospect Street and chased it to the 3200 block of Whitehaven Parkway, where two men got out and scaled the observatory fence.

About an hour later, a police dog cornered a man in a woods near a maintenance shed, where police found a gun and jewelry taken during the robbery, Waybright said.