At 5 a.m., Pasadena police responded to a 911 call in the 70 block of Harkness Avenue.
An armed resident, known to police, answered the door, but went back inside. Officers evacuated the other residents and tried to contact the armed suspect.
Police are currently firing concussion grenades.
SWAT meeting with Police Chief Sanchez
Suspect is an Asian male armed, still barricaded.