The gunman, described as a scruffy, dark-haired man in his thirties, entered the office at the North Lake shipyard, on Lake Union, to the north of downtown Seattle, and began firing at employees with a handgun. Wearing sunglasses and a moustache, a camouflage shirt, dark trousers and a cap, the killer said nothing as he carried out the attack and did not appear to be known to his victims.
"He walked in and started shooting. That's all we know," said a police spokeswoman.
One of the victims died on the spot, while a second, hit three times in the chest, died during surgery at a local hospital. Police launched a massive manhunt in the Wallingford area immediately next to the shipyard, using sniffer dogs but after several hours were still empty-handed. At least a dozen schools in the search area were "locked down" with the children inside while the search continued, police said.
The attack came one day after a photocopy repairman opened fire on his colleagues at the Xerox company in Honolulu, Hawaii, killing seven of them. He later gave himself up after a five-hour stand-off with police in a nature reserve.
A shocked President Bill Clinton addressed the nation, saying: "Our thoughts and prayers are with the victims and their families."
America has been swept by random shootings in recent months, from an attack on a Baptist church in Texas in September, in which eight people died, to the rampage by a bankrupt day-trader in Atlanta in July, which left 12 people dead.