Firefighters have reopened a Kakaako office building that had been evacuated this morning after an office received a letter containing a suspicious substance.

Fire Capt. Terry Seelig said hazardous materials teams determined there was no credible threat and turned the building back to management at about 12:30 p.m.

Firefighters responded to a call at the Standard Financial Plaza at 715 S. King St. about 10:30 a.m. after the Honolulu Police Department Career Center reported receiving a letter containing a suspicious substance.

Seelig said two hazardous materials teams and two engines responded.

Because the building's sole ventilation is a central air conditioning system, all occupants were evacuated. Workers on the fifth floor, where the letter was received, were isolated from the others.