One exit was blocked by beer crates and employees’ lockers. The low ceiling was covered in flammable foam used to soundproof the venue. And there were no sprinklers.

These apparent lapses, described by fire safety experts and witnesses, likely contributed to the deaths of at least 30 people at the Rong Beer Na Lat Phrao bar in Bangkok on Sunday night.

While investigators have not yet provided a comprehensive account of what caused the fire, interviews with survivors, officials and experts suggest the lapses were similar to ones that have led to deadly infernos in nightclubs and bars in countries all over the world. To some, it called to mind the New Year’s fire in a bar in a Swiss Alpine resort that killed at least 40 people this year. Similar deadly episodes have occurred in Rhode Island, Brazil and elsewhere in Thailand.

“Lessons from these fires should be learned, but they are not,” said Richard Meier, a fire investigator in Palmetto, Florida, who works across the United States.

The fire in Bangkok most likely began with an electrical short circuit in an air-conditioner installed in the ceiling of the bar, Suriyachai Rawiwan, a local disaster prevention official told reporters on Monday. Fire safety experts said the ensuing sparks likely shot up into the ceiling, setting alight the flammable foam that covered it.

The main entrance was a narrow door close to the venue’s stage where the fire apparently started while a band was playing. The door was consumed by a horizontal plume of fire that shot out like a jet stream of flames, footage showed. Panicked revelers rushed toward the back of the building for safety. The fire raged for about half an hour before it was put out, according to local news media.

The ‘Flashover’ Phenomenon

Nuttapol Lerkkasemsan studies flammable materials at King Mongkut’s Institute of Technology Ladkrabang in Bangkok. After reviewing footage of the fire shared on social media, he said it was clear to him that a so-called flashover — the rapid spreading of a fire in an enclosed space — had occurred. At the Bangkok bar, he said, flammable gas most likely released by heated foam panels got trapped in the ceiling, igniting a huge blaze that spread across the venue within seconds.

“People inside had no chance to escape anymore,” he said. “The temperature rises to several hundred degrees Celsius.”

One investigator, Juladit Chayaniyayodhin, a fire protection specialist with the Engineering Institute of Thailand, a nonprofit, said in an interview after inspecting the bar that it did not have any sprinklers installed. A survivor, Atipat Wijan, said he did not see any sprinklers going off after the fire.

The governor of Bangkok, Chadchart Sittipunt, told reporters on Tuesday that the authorities would start conducting inspections on all entertainment venues in the capital. A day earlier, he had said that the condition of many venues during an inspection was “not necessarily the same as during actual operation.”

Local news outlets have suggested that many entertainment venues temporarily comply for scheduled inspections, only to change their setups, potentially in unsafe ways, once they have secured their permits.

An official from the Bangkok Metropolitan Administration who was guarding the site on Monday night said that Rong Beer had recently had an inspection. He did not say what the inspection covered but said that he and his colleagues had called the owner of the bar in advance to arrange a time for it. The official, who was wearing a uniform, declined to give his name, saying he was not authorized to speak to reporters.

The bar was in the Lat Phrao district in northern Bangkok and was about two years old. It was popular with people in their twenties, many of whom worked at a nearby mall. The bar offered affordable food and drinks and live bands that played most nights.

The Foam-Covered Ceiling

To soundproof its premises, Rong Beer used foam padding on the ceiling — a fact fire safety experts zeroed in on.

A cheap insulator that is used by many karaoke bars and nightclubs for soundproofing, it is extremely flammable and can emit toxic fumes when ablaze.

“Once the fire starts, the foam basically will make a small fire an inferno,” said Xinyan Huang, an associate professor and fire safety engineer at the Hong Kong Polytechnic University.

Mr. Huang said this kind of foam has accounted for a sizable chunk of the deadliest nightclub fires around the world in recent years.

The problem is so bad that Steven Badger, a lawyer based in Dallas with expertise on cases involving indoor fires, said that whenever he sees foam soundproofing in a venue, he immediately leaves.

“People putting up the foam don’t know how dangerous it can be. But the building officials from the government should know,” Mr. Badger said. “It is surprising to me that any code official, who goes into a building, would not identify the presence of these materials, and ask that they be removed.”

Blocked Rear Exits

Survivors, officials and experts also called attention to the doors at the back of the venue. One rear exit, near the kitchen, was blocked by beer crates, shelving units and employee lockers, according to Thailand’s police chief, Kitrat Phanphet. Another exit was obstructed by a table where candy was being sold, according to Kaewudon Pungpanee, an employee who made it out of the bar.

When Prime Minister Anutin Charnvirakul toured the site of the blaze early on Monday, an official told him that one of the rear exits was found locked with two physical bolts, according to television footage. Officials have not yet confirmed if that was the case.

On Tuesday afternoon, many relatives of the victims were still waiting for news about their missing loved ones at Bangkok’s police hospital. Two dozen people remain in critical condition, according to officials, who said all those who died and were injured were between 25 and 40 years old.

At the bar, people had laid down flowers and jasmine garlands as tributes to the victims.

Khaek Phommasongsa, a cook at an open-air restaurant across the street, said he had broken a window at Rong Beer on Sunday night to try and rescue some friends who were inside.

One of them died, another was being treated in intensive care and yet another remained missing, Mr. Khaek said. Reports that the exit doors were blocked made him angry, he said. “It’s not OK. Why would anyone do this?”