Missing 7-year-old Kai Park with blue hoodie

I'm Mia Park, Kai's mom, and I lost my son yesterday around 4pm. Last seen near Powell's City of Books on West Burnside in Portland, he wore a bright blue hoodie with a yellow star patch, gray sweatpants, and black sneakers. Kai is 7 years old, about 4 ft 4 in, with short black hair and a small star-shaped birthmark on his left wrist. I'm really worried—he can be curious and shy, and the busy crowds around the Pearl District make it easy for him to slip away.