At least 27 people were killed and 22 others were critically injured after a devastating fire tore through a popular bar in Thailand’s capital, Bangkok, shortly after midnight on Monday.

The fire started close to the stage of the Rong Beer Na Lat Phrao, in the bustling area of Chatuchak district, and soon engulfed the venue. The fire quickly caused a loss of electrical power to the building, and spread heavy smoke throughout the bar, sparking panic among patrons, witnesses said.

Terrified customers in a Bangkok bar yelling and running toward the exits have been seen in social media video footage, some of whom were running with clothes on fire.

The fire was quickly extinguished after fire officers arrived in about 30 minutes. In an area there were many casualties who reported having sought shelter in a bathroom as they were trying to leave the fire, officials said during rescue operations.

The preliminary investigation of Bangkok’s disaster mitigation department indicates that the fire could have been caused by a short circuit of the electrical system in an air-conditioning unit. But the details would be known after a thorough investigation, authorities said.

PM Anutin Charnvirakul went to check the area to announce that a musician on the premises described hearing a big explosion, followed quickly by smoke and flames which engulfed the building. It was reported that many people had gone running towards the back of the bar only to be trapped.

Nine men and 18 women were killed in the tragedy, officials said. There have been over 60 hospitalisations, 22 of whom are in a critical condition.

The incident has again sparked concern around the nation over fire safety standards and enforcement in Thailand, and police have said they will see to it that a complete investigation is carried out.