A gunman walked into an office building near a shipyard here this morning and opened fire on a group of workers, killing two and igniting a massive manhunt that kept students cowering inside neighborhood schools and police officers searching door-to-door for the suspect.

Late tonight, police in Tacoma, about 25 miles south of here, pulled over a vehicle and detained a man described as a "person of interest" in the case, according to Pam McCammon, Seattle police spokeswoman. The man was to be transferred to the Seattle Police Department, whose detectives were to question him.

The gunman was wearing a dark trench coat over camouflage clothing when he entered an office at the Northlake Shipyard here about 10:30 a.m. (PST), police said, pulled out a 9mm handgun and shot four people--all employees--who were there. Peter Giles, 26, died at the yard his uncles owned. Russell James Brisendine, 43, died later in surgery.

It was the second workplace shooting in the nation in two days, coming about 24 hours after a disgruntled Xerox technician in Honolulu shot and killed seven of his co-workers. The incidents are the latest in a string of multiple shootings in the workplace and at schools this year.

President Clinton, answering questions from reporters at the White House, said he was shocked and saddened by yet another instance of a seemingly random multiple shooting.

"But let's not forget, 13 of our kids get shot every day, killed every day," Clinton said. "And just because they die one and two at a time in distant places or tough neighborhoods . . . we're almost inured to it. I don't think we understand fully just how much more violent the United States is than other countries.

"But I think we have to acknowledge the fact that we have been willing to tolerate a much higher level of violence than we should have."

Seattle police weren't able to say whether the gunman had worked in the office or at the shipyard, but the surviving victims, whose ages--19 and 58--but not names were released, did not recognize him.

Norm Eckert was in his office above the one where the shootings happened this morning when he heard what "sounded like a nail gun," he said. "Noises like that are not unusual." Then, he heard several police cars.

He and his partner watched from a window as emergency workers took three injured men out to ambulances. "Then one person was not removed," he said. "It's just hard to believe. To think this has happened is beyond grasp, at least for me.

"We know [one of the men] we think has been killed. I've seen him at basketball games and around town. He was always a friendly, upbeat person."

Jeannie Parr, who works in a glassed-in office across the hallway from where the shootings occurred, told the Seattle Times that she saw a man whom she had noticed earlier walk calmly into the building.

"He just doesn't quite fit with the fishing industry, with the people who work down here," Parr said. "So it was noticeable."

Moments later, Parr said, she heard numerous gunshots and looked into the office across from hers.

"I saw a fellow hanging out the window who had been wounded and he kept saying, 'Call the police, call the police,' " Parr recalled. She then went over to the office.

"One of them I was trying to help . . . his eyes were open, but he was not talking," Parr said. "I kept asking him to squeeze my hand and hold on. His eyes were moving, but it was not like he was really hearing me."

Seattle Police Chief Norm Stamper said in late afternoon here that they believed the gunman was still in the area. City officials urged residents in the neighborhood to call police if they noticed anything out of the ordinary when returning to their homes from work. The late-morning shooting emptied streets in the adjoining residential neighborhoods, as residents chose the safety of their homes to a chance encounter with a man police were describing as "armed and dangerous."

The Northlake Shipyard sits on Lake Union, facing the Seattle skyline. The Space Needle can be seen from the two-story office building where the shooting occurred. Most of the offices in the building house marine-based businesses that service the ships that dock to the rear of the building.

The search--still focused largely in the shipyard area--continued into the night. "This is a serious shooting; we're not just going to let him go," Stamper said.

Staff writer Cassandra Stern in Los Angeles contributed to this report.

CAPTION: Rampage victim Peter Giles in an undated photo. He was 26.

CAPTION: Medical personnel carry a shooting victim into Harborview Medical Center in Seattle. The assailant fled, igniting a massive manhunt.

CAPTION: Victims' relatives rush to the Northlake Shipyard in Seattle after the shooting.