(SeaTac, WA) -- King County investigators are looking for suspects in connection with the theft of about 400-thousand-dollars worth of diamonds in SeaTac, Washington. Deputies say two diamond couriers, who were in the Seattle area from Hong Kong to sell the diamonds, were held up earlier this week by three masked men. Officials say one of the suspects cut off the victims' vehicle along an Interstate 5 ramp while another pulled up behind the victims' car and hit it. Deputies say the thieves broke out two windows in the victims' car, assaulted the driver and grabbed a backpack containing the diamonds. Authorities say a third suspect kept a gun pointed at the victims as they were being robbed.