The violent incident happened Tuesday before 7:30 a.m. at a home in the 2600 block of Northeast 195th Street.
The residents told police three men -- two armed with handguns -- came into the house and began pistol whipping the roommates as they slept.
The robbers stole several undisclosed items and threatened to kill the roommates before leaving, according to Lake Forest Park Police Chief Steve Sutton.
Sutton said one of the victims -- a young woman -- had been dating one of the attackers, who still had a key to the home.
"This was an ex-boyfriend that was mad at the girlfriend, who had a new boyfriend," Sutton said. "He had a key to that apartment still, and he brought two other people with him and I guess did a little vengeance on the ex-girlfriend and her new boyfriend."
One of the three roommates was taken to a local hospital to be treated for non life-threatening injuries.
Police believe they know who two of the attackers are, and they're asking for help from the public to track them down. Sutton said hostage negotiators reached one of the suspects by phone on Wednesday, but they weren't able to convince the man to turn himself in.
Police are now looking for 24-year-old Able Gebregergish and 22-year-old Aron Gebregergish. Able stands 5'8" tall and weighs 165 pounds, while Aron stands 5'10" tall and weighs 230 pounds.
Sutton said both men should be considered armed and dangerous. Anyone who sees them should call 911.
Police have yet to identify the third alleged attacker.