GROTON, Conn. (WTNH) — A fire investigation is underway after flames broke out at an apartment building in Groton.

Crews responded to an apartment building on Thames Street around 4:30 p.m.

The fire chief said the fire started in the back of the building and then spread.

Four apartments are now unlivable, according to fire officials.

No additional information was immediately available.

This is a developing story. Check back for updates.