SPOKANE, Wash. — Building tenant Lisa Milliken has been arrested for first degree arson following the apartment fire that broke out at an apartment on 2nd Avenue and Pine Street, officials said.

Officer Casey Jones, responded ro an unrelated call in the area, spotted Milliken walking in an alley near the apartment building as he saw smoke billowing from what was later determined to be her apartment window. After a brief conversation with Milliken, she was released pending further investigation, officials said.

Officials said when they arrived, two units were on fire. Between 50 and 55 firefighters were dispatched to the scene and quickly got the fire out. Crews also used a drone to help investigate.

Authorities said several residents were displaced by the fire.

One resident said, "I saw these two windows explode and glass come out….it was very dark and black,"

The cause of the fire is under investigation.

While conducting interviews and reviewing evidence, witnesses alleged the night before Milliken had threatened to burn the building down, officials said. Fire Investigators determined an “incendiary device” had caused the fire. Based on that information, officers booked Milliken for 1st Degree Arson just after 3:00pm Monday.

Milliken will be in court Tuesday at 1:30pm.