Police were initially called to the 100 block of West Hill Street at 7 p.m. after witnesses spotted a man walking in the alley with a knife.
Officers soon learned that the man was suspected of stabbing his 34-year-old wife several times while she was working at a shop on North Lewis Street.
She was airlifted to Harborview Medical Center with critical injures.
Officers tried to get the man to put down the knife and surrender, but he refused. Police briefly followed him as he walked down Blakeley Street with the knife to his own throat.
The entire scene played out in front of shocked witnesses, including Danny Smith.
"I started yelling, 'Get on the ground,' and he held the knife up to his throat," Smith said. "It was a big knife, it was huge. He was waving it and swearing and cussing and waving the knife around."
Police eventually subdued the man using a Taser. The alleged attacker was injured during the arrest and was also taken to Harborview.