Officers were called to the area near 12th and Dearborn just after 11 a.m. for reports of shots fired. The suspected shooter ran away on foot, crossing I-5 in the process, said Mark Jamieson with Seattle police.
Officials shut down the ramp from I-5 north to eastbound I-90 and the off-ramp from I-5 to South Dearborn Street as police conducted their search for the gunman.
The man was captured around 12:40 p.m. near 13th Avenue South and South Dearborn Street, Seattle police said.
There are no reports of anyone wounded by the gunfire.