Eight armed robberies occurred in Washington in a three-hour and 38-minute period yesterday, a rate that is about 2 times the current rate average of about 20 armed robberies a day.

A robbery victim was shot in one of the holdups and a suspect was arrested in each of two others. The eight holdups occurred between 8:42 a.m. and 1:20 p.m.

Ronald E. Crytzer, head of the police department's robbery squad said that a seasonal increase in armed robberies is normal, if undesirable, at this time of year. But he added that the increase this year has been the steepest in his recollection.

The police official said he could not cite a specific cause for the rise.

The victim who was shot was identified as Frank Rochelle of Baltimore, an employe of Car Plaza at 601 New York Ave. NW. He was listed in stable condition at the Washington Hospital Center after being shot in the neck.

A shot was fired during the holdup at the Atlantic Parking Garage, 943 New York Ave. NW, at 8:42 a.m. when a robber struck an employe with a gun and the gun weapon discharged. A man seeking treatment later at D.C. General Hospital for a gunshot wound was arrested and later charged with robbery in the garage incident, police said.

An owner of the B&L liquor store, 911 11th St. SE, pursued a robber from the store about 11:33 a.m. yesterday, and when the robber whirled to face him with a gun, the owner fired three shots from his own weapon, police said.

A man with a wound in the leg was later arrested and charged with robbery in that incident, police reported.