An unidentified man who disrupted a Rockville Pike real estate office last night was shot and critically wounded in a confrontation with a Montgomery County police officer, police reported.

The shooting occurred about 8:45 p.m. in a Long & Foster office in the 11600 block of the Pike, just north of the White Flint shopping center.

The victim, who appeared to be in his late thirties or early forties, was in the intensive-care unit at Suburban Hospital in Bethesda late last night with a wound in the chest and a grazing wound on the right arm.

According to a county police spokesman, the real estate office, which normally closes at 7 p.m., was open last night for a business transaction when the incident occurred. Two real estate agents were inside with two clients, and a third agent was entering the office, housed in a one-story detached building with a peaked roof.

As the agent walked in, a heavy-set man walked in behind her.

Agents told the man that the office was closed. The man appeared to disregard the statement, according to police, and remained inside. Muttering and mumbling unintelligibly, he knocked over some furniture. One of the real estate agents telephoned police to report what the police spokesman, Sgt. Harry Geehreng, described as disorderly behavior.

Officer Robert Hellmuth arrived within minutes, the spokesman said. The officer, who was described as experienced, found the man "acting violent," Geehreng said.

"The man came toward the officer and there was a confrontation," Geehreng said. However, he said he could give no details of the events immediately before the shooting, which he said took place 20 yards or so into the office.

A source familiar with the police investigation indicated last night that the man, described as about 6 feet tall and 200 pounds, was not carrying a weapon.