Becky Neher, who works for a title company in the building, said the two gunshots she heard sounded like two pieces of metal banging against each other.
Watching from her second-story office, she saw people leaving the building.
"Someone yelled, 'We have a shooter,'" she said. She saw two victims lying on the ground outside the back side of the building. She said health care workers who have offices in the complex came out to help.
Don Jaksa, a software consultant who works in the building, said he was listening to the radio when he suddenly heard "two pops." He said he didn't think they were gunshots.
"My co-worker goes to the range all the time," he said. "He identified it as gunfire."
His co-worker then locked the door. After five minutes, they left and ran into police and someone carrying a stretcher. The police escorted them back to their office and told them to lock the door again.
They were eventually evacuated, and as he sat on a rock outside the complex, his wife called to make sure he was OK after seeing the shooting on the news.
Workers were later allowed to leave the building. Two hugged each other when they got outside.
"You don't expect this when you come to work," worker Lindsa Rincon said.
Associated Press writers Paul Davenport, Felicia Fonseca and Terry Tang contributed to this report.
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