With patrol car sirens screaming and lights flashing, scores of police officers hunting suspects in a string of street robberies last night mounted a massive search through elegant Cleveland Park that included a tree-by-tree combing of the grounds of the vice president's home.

Reports of at least four and possibly as many as six apparently related robberies along upper Embassy Row and the surrounding area brought a huge police presence that included a helicopter and half a dozen dogs, and prompted stunned passengers in a passing tour bus to open windows and ask: "What's going on here?"

Too busy to answer, police searched woods along Massachusetts Avenue opposite the Naval Observatory site where Vice President and Mrs. Bush reside, while uniformed agents of the Secret service picked their way through the grounds of the sprawling compound.

The late night manhunt that turned the quiet and prosperous neighborhood into a scene of tense drama was touched off by reports of two robberies on Wisconsin Avenue, one on Newark Street and another on Massachusetts yavenue near the British Emb assy -- all within a few minutes of each other between 10 and 11 p.m.

In one of the robberies, two men accosted Larry Marscheck on Newark Street near 35th Street NW. One of the men asked Marscheck recalled, the men began running towards him. One of them was armed with what appeared to be a silver-colored revolver. It might have been a toy, Marscheck recalled thinking, "but I couldn't tell."

"Don't move. Hold it," ordered one of the robbers.

Marscheck complied.

One of the robbers emptied Marscheck's right front trousers pocket of 12 cents. The other reached into Marscheck's left rear trousers pocket and took his wallet, which contained $20.

The robbers told Marscheck to walk straight ahead. He took a few steps, and they fled.Then he ran to his home nearby and telephoned police. Three police cars arrived within two minutes, Marscheck said.

As he talked with the officers, their radios crackled with reports of other, similar robberies in the area.

The last of the robberies took place at 10:42 p.m. in the 3300 block of Massachusetts Avenue, which is between the British Embassy and the Naval Observatory where the vice president's house is located. Shortly after that holdup, police stopped a car nearby.

A man emerged from the car, ran toward the grounds of the vice president's home and began climbing the iron fence that surrounds the compound, a White House spokeswoman said.

That act automatically triggered the high-intensity security lights that ring the grounds.

Startled and bewildered, the man clambered down from the fence and fled, according to the spokeswoman, Sue Mathis.

He "really didn't realize where he was," Mathis said.

That incident and the proximity of the other robberies touched off the search of the grounds. Authorities said it finally was determined that aside from the brief moment at the fence there had been no penetration of the heavily secured area.

It was believed that neither the vice president nor Mrs. Bush was at home at the time.

After stopping the car on Massachusetts Avenue, police arrested the driver, Rita Hutchinson, 26, of 4069 Minnesota Ave. NE. Subsequently, police said, they arrested Ricky Abney, 25, of 1109 4th St. SE, and Larry Freeland, 28, of 4628 Livingston Rd. SE. One of the men was spotted by off-duty officers about 11 p.m. as he emerged from woods near where the car was stopped. The other was seized on Massachusetts Avenue a short distance from the scene.

Police said each of the three was charged with one count of robbery.