The fire, near the Rainier Yacht Club on Seward Park Avenue South, was reported around 9:45 p.m.
In addition to the three boats, an overhead marina structure, essentially a roof on stilts, was ablaze late Sunday, said Kristin Tinsley, a Fire Department spokesperson.
At 10:30 p.m., Tinsley said there were no reported injuries, although a search of the area was not yet complete. At 11 p.m., the Fire Department said on Twitter that the boats could not be searched due to fire damage.
The two people on the dock were past the point of the fire and were “instructed to stay in place” until it was safer to come back to shore, Tinsley said.
The three boats were “pleasure craft” and pretty small, Tinsley said.
Shortly before 10 p.m., the Fire Department reported it had “water on the fire.” At 11 p.m., the department said the fire was under control in approximately one hour.
The fire was blocking traffic on Seward Park Avenue South, between Rainier Avenue South and South Fisher Place, according to the Seattle Department of Transportation. All lanes reopened overnight.
At least 11 engines and three ladder trucks responded, as well as fire boats from the Fire Department and Seattle police.