“My heart right now is with the victims and their families and with everyone in our community who is reeling from what happened here today,” she said at the news conference.
In a statement earlier, she thanked first responders, including firefighters, event staff members and bystanders who helped people get to safety, as well as hospital staff members who treated the wounded.
The Seattle office of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives said on X that some of its special agents were at the scene assisting Seattle police with the investigation.
Rep. Pramila Jayapal, D-Wash., said officials would work to get federal resources.
The food festival was wrapping up its annual event Sunday, the final of its three days.
Estan Wakonabo was waiting in line with his girlfriend for a photo booth when people around them started running furiously, he told NBC affiliate KING of Seattle.
“It was a stampede,” he said.

Not long afterward, Wakonabo said, he noticed people on the ground, some with obvious gunshot wounds.
“There’s bodies everywhere,” he said of those on the ground who appeared to be injured. “I mean, I counted eight.”
Paul Skinner was helping operate a Bite of Seattle booth for the food truck Crave when chaos erupted, he said.
“We just heard what at first sounded like firecrackers, but it’s just a little too crowded for that kind of thing,” he told KING. “So then, when the crowd started moving quickly in herds, you knew it was something was happening.”
He added, “We all got down and took cover.”
The entrance to Bite of Seattle at Seattle Center on Sunday.Lindsey Wasson / AP
Isaiah Flores Sanches described hearing the gunfire.
“It went from something being so playful and so joyful to being something so horrific, and I seen people on the floor trying to take cover,” he told KING.
Bite of Seattle says it draws more than 350,000 people to its annual three-day festival, for which admission is free. “The Bite of Seattle is a very positive event,” Davis said. “We haven’t had any issue in recent years.”
Organizers did not immediately respond to a request for comment.
The civic center complex that grew into Seattle Center included core structures erected for the 1962 Seattle World’s Fair, including the Coliseum, the Seattle Center Monorail and the Space Needle.