Police arrested Naveed Afzal Haq, 30, after the shooting Friday afternoon and he was booked for investigation of homicide and attempted homicide, police said. They were investigating the shooting as a hate crime.
Haq was expected to make an initial court appearance Saturday afternoon.
The gunman forced his way through the security door at the federation after an employee had punched in her security code, Marla Meislin-Dietrich, a database coordinator for the center who was not at the building at the time, told The Associated Press.
"He said `I am a Muslim American, angry at Israel,' before opening fire on everyone," Meislin-Dietrich said. "He was randomly shooting at everyone."
Police would not confirm the account.
Pam Waechter, 58, an assistant director at the federation, died at the scene, said Nancy Geiger, the Jewish Federation of Greater Seattle's interim chief executive.
"This is just an extraordinary shock. We lost a really wonderful colleague, a wonderful friend. It's hard," Geiger said.
As employees fled the center, a police commando team raced to the scene and cordoned off several downtown blocks. The gunman surrendered moments later after speaking with a police emergency dispatcher. That conversation led police to believe the shooting was a hate crime, authorities said.
Five other women were shot, including a 37-year-old who is five months pregnant and was hit in the forearm. She was in satisfactory condition, along with a woman who was shot in the knee. Three others were shot in the abdomen and were hospitalized in serious condition.
Jewish leaders are concerned because of a recent videotape in which a leader of a terror urges Muslims around the world to take their battle to America, reports CBS News correspondent Sandra Hughes.
"What concerns me is whether this is an isolated incident — which I seriously hope it is — or whether it is a pattern of something beginning," John Fishel, president of the Jewish Federation of Greater Los Angeles, told Hughes.
Seattle Mayor Greg Nickels and Police Chief Gil Kerlikowske said officers were moving to protect synagogues and mosques around the city, but said there was no evidence of a broad conspiracy.
"This was a purposeful, hateful act, as far as we know by an individual acting on his own," Nickels said.
Authorities have been advising synagogues and Jewish groups to be watchful in the weeks since hostilities erupted between Israel and Hezbollah guerrillas in Lebanon. Assistant Police Chief Nick Metz said the warning was not in response to any specific threats.
Kerlikowske said police were protecting mosques "because there's always the concern of retaliatory crime."
When asked if the suspect was Muslim, Kerlikowske said at a news conference, "you could infer that that was his background." Laura Laughlin, special agent in charge of the Seattle FBI office, said Haq was a U.S. citizen.
Haq's lawyer, Larry Stephenson, told The Seattle Times that he thought Haq was single and unemployed, and that Haq had a misdemeanor lewd conduct charge pending in Benton County. Haq had been accused of exposing himself in a public place, Stephenson told The Times.
Haq's parents were shaken by his arrest in the shootings, the lawyer said.
"I talked to his father, and his mother is crying, and they don't know what is going on," Stephenson said. "They are very, very shook up."
Yousef Shehadeb, 46, a member of the Islamic Center of the Tri-Cities, recalled Haq as quiet and something of a loner. Shehadeb said he and Haq's father, Mian Haq, both work at the Hanford nuclear reservation, as do many members of the area's Muslim community.
No one answered the door to an Associated Press reporter on Saturday at the Haq residence north of Pasco.
Shehadeb had not called the Haqs, he said, because "I didn't know what to say."
In a statement, the Islamic Center offered condolences to the shooting victims and said "we disassociate this act from our Islamic teachings and beliefs."