Vietnam has ordered an investigation into a blaze which killed 13 people at a karaoke bar, officials said on Wednesday.
Most of the dead were government workers at a staff party being held in a multi-storey building in Hanoi's commercial Cau Giay District.
The fire started around lunchtime on Tuesday and flames quickly spread to engulf three neighbouring buildings as clouds of black smoke filled the air, a witness said. The blaze took five hours to extinguish.
"Hundreds of firemen and police officers were mobilised to extinguish the fire," said a ward official, The Chung. He added that two police officers were being treated for injuries sustained while trying to douse the flames.
Vietnamese Prime Minister Nguyen Xuan Phuc has ordered police to immediately investigate the cause of the fire and "seriously punish wrongdoing," according to the government's website.
He also told local authorities to closely inspect karaoke bars and restaurants for fire safety and equipment and shut down the outlets that failed to meet fire preventive measures.
State-run media quoted an official as saying 11 of the victims were government employees.
"They went out partying after finishing a test during a political training course," Hanoi's party chief Hoang Trung Hai said, according to newspaper Tuoi Tre.
He said the fire might have been sparked by construction inside the building and trapped patrons likely suffocated inside the windowless karaoke rooms.
"I was carrying my stuff when I saw the fire suddenly start," said Do Thi Kha, 77, a food vendor in the area.
"The fire spread over to two or three neighbouring buildings before I saw fire trucks come in. It was terrible. I was terrified. They did not have enough water to extinguish the fire," she said.
Another witness said the fire burned for more than five hours and was made worse when it ignited fuel tanks in cars parked nearby.
"Trucks had to keep coming back and forth with water as there was not enough. That was why it took so long to extinguish," said 69-year-old Nguyen Dinh Sau.
Karaoke bars are popular hangouts in communist Vietnam, among government officials and young people alike, and Tuesday's fire was not the first of its kind in the capital.
In May 2014 five people burned to death at a karaoke bar in Hanoi after an electrical fault triggered a massive blaze.
Another karaoke venue in the city went up in flames in September this year, but no casualties were reported from the incident.
Fires are common at houses, bars, and restaurants in Vietnam, where fire prevention and firefighting is limited.