Over 40 people were injured following a major explosion at a two-story izakaya bar in the Japanese town of Sapporo, Hokkaido on Sunday evening.

Police are investigating the cause of the blast, currently believed to be a gas explosion at approximately 8:30 p.m. local time at the izakaya Umi Sakura - a bar close to the Sapporo subway line's Hiragishi station.

The explosion caused the 66-seater eatery to collapse. It also shattered the windows of nearby apartments and food and beverage outlets. The Hiragishi district is less than 15 minutes by train from the main Sapporo station that serves the capital city of Hokkaido, Japan's northernmost prefecture. -Straits Times

Evacuation orders have been issued to nearby diners and residents who were warned of further explosions by police and first responders.

WATCH: Firefighters battle flames and thick smoke after a huge explosion levelled a restaurant in Sapporo: https://t.co/lYKuaoKRdP



(Video: Twitter/Syurikenbouya) pic.twitter.com/5Qbc5uYGXn — Channel NewsAsia (@ChannelNewsAsia) December 16, 2018

Local residents likened the blast to a missile strike, thunderbolt, or an earthquake, while those on the street reported a lingering, pungent gas smell.

Massive explosion has ripped through a restaurant in #Sapporo, northern #Japan. Preliminary reports of at least 40 injuries. pic.twitter.com/eUKPpIkN0H — World News (@worldnewsevery) December 16, 2018

A women in her 70s was quoted by the Mainichi Daily as saying "The restaurant entirely disappeared without a trace, while the roof of the family restaurant next door also collapsed," adding "I'm at a loss for words to describe how I feel about the scale of this catastrophe."

A waitress was told to jump off the second floor to escape the inferno according to NHK, citing her older sister. "She was told to jump off from the second floor, where she had been, and so she did. It seems like she broke her leg, but I am just thankful that she is alive."