Her body was discovered by the girl's boyfriend around 8:30 a.m. in the 1600 block of 22nd Ave. NE, said Cmdr. Steve Stocker with Auburn police.
A man suspected in her death was arrested a short time later at the bus top outside the Top Foods market on Auburn Way N., police said. His identity has not been released but police say it was the victim's ex-boyfriend.
Police say the girl's boyfriend was in the house at the time of the attack but was asleep and didn't hear anything.
Detectives have not released any information on what led up to the stabbing.