The first round was a phone interview by an actuary from the firm which lasted about half an hour. The interview was mainly to get to know you/why you want to be an actuary, find out what you know about the actuarial profession/what CIA and SOA are for and a couple of simple behavioural questions.
The second round was onsite in Seattle. I had 4 interviews with 5 interviewers throughout the day, each 50 minutes long. All of the questions were behavioural-based. Two actuaries also took me to lunch.