Popular dim sum eatery Hong Kong Lounge II (3300 Geary Blvd., at Parker Ave.), appears to have suffered a serious explosion this afternoon, around 1:30 p.m. Its structure is currently ablaze in what the SFFD has said is a two-alarm fire.

It's unclear if anyone has been harmed in the blaze. The restaurant is typically open from 10:30 a.m. to 2:30 p.m. on Wednesday afternoons, meaning patrons could have been inside for lunch service at the time of the explosion.

As firefighters respond, adjacent traffic is being diverted to avoid the area. Witnesses posted footage of the incident to social media.

Was just having lunch when we heard an explosion and saw huge flames shooting out from the street on Geary in front of Hong Kong lounge 2. Hope no one got hurt. It was surreal. #explosion #SanFrancisco #gearystreet pic.twitter.com/xzrZRq1IsA

— Telmo Faria (@ChefTelmo) February 6, 2019

@Hoodline oh no Hong Kong Lounge 2 just caught fire!! :( pic.twitter.com/lS2GuIVWZW

— One Night Only SF (@OneNightOnlySF) February 6, 2019

We'll continue to update this post as we learn more about the cause of the explosion and the fire's severity.

Update, 2:15 p.m.: A spokesperson for the Fire Department says that the fire's severity has been raised to three alarms, as firefighters continue to battle the blaze. 

The source of the fire has been confirmed as a gas explosion, involving Hong Kong Lounge and three additional buildings on the block. All buildings within a one-block radius are being evacuated by police and Fire Department officials. 

While five construction workers were initially unaccounted for in the wake of the fire, they've been located and identified as uninjured. There's still no word on whether anyone else has sustained injuries in the fire. 

Update, 2:20 p.m.: The 38-Geary Muni bus line is being rerouted due to the fire: 

UPDATE: Reroute changes - IB now routing via 2nd to TURK to Masonic back to Geary; OB now routing via GEARY to PRESIDIO to CALIFORNIA to ARGUELLO back to Geary. https://t.co/YYltFZmj5C

— SFMTA (@sfmta_muni) February 6, 2019

Update, 2:53 p.m.: According to San Francisco fire chief Joanne Hayes-White, the explosion was caused by eight construction workers were digging in the ground to install fiber optic cables when they hit a gas line. All eight workers have been accounted for safely.

Update, 4:27 p.m.: The Fire Department reported full containment of the fire shortly after 4 p.m., advising that the street would remain closed at least until 8 p.m. tonight. No injuries are reported.

#020619WF2 UPDATE FIRE CONTAINED NO INJURIES 5 structures involved expect complete road closure for 4 hours minimum - under investigation Media update at 430 pm Anza and Parker pic.twitter.com/KszvzbJgi9

— SAN FRANCISCO FIRE DEPARTMENT (@SFFDPIO) February 7, 2019