PITTSBURG (CBS SF) -- Firefighters battled a 2-alarm blaze that erupted and quickly spread through an addition under construction to church Friday morning.

Contra Costa Fire officials reported the blaze at around at 6:53 a.m. in a neighborhood of commercial and residential structures in the 300 block of Central Ave.

The intensity of the flames and threat of collapse forced firefighters to take a defensive approach.

The 300 block of Central Ave was closed off, motorists were asked to avoid the area. By 9 a.m., Confire tweeted that crews had extinguished the fire and were mopping up.

A cause of the blaze was under investigation. No injuries have been reported.