5:35 PM: Seattle Fire is sending a water-rescue response toward Seacrest by land and sea after a report of a possible overturned kayak with two people aboard. Updates to come.
5:38 PM: Firefighters arriving at the scene say two people have been rescued by other kayakers, one already towed in and one more on the way. The big response is affecting street traffic, so avoid the area for a while.
5:41 PM: Both rescued kayakers are reported safely ashore and SFD is canceling all but two of its responding units.
ADDED: Jen from Alki Kayak Tours says in a comment below that the people in trouble were in a skiff, not a kayak, and that AKT employees rescued them.