Investigation underway after crews battle house fire in Redwood City

REDWOOD CITY, Calif. (KGO) -- An investigation is underway in Redwood city into what may have sparked a massive house fire Tuesday afternoon.

It started around noon on Poplar Avenue near Addison Street.

SKY7 was over the scene as smoke billowed into the air.

The home has construction going on in the back and neighbors say they heard an explosion right before the fire started.