A fourth child has died from injuries suffered last week when his family's house was on fire in the middle of the night, officials said Tuesday.

Year-old Mauj CagTxuj Vaj died at Regions Hospital late Saturday, police Sgt. Mike Ernster said.

Ker Lor and all of her six children — three boys and three girls — were found on the first floor by firefighters and hospitalized after the early morning fire on Jan. 3 at their home in the 1200 block of N. Arkwright Street in the Payne-Phalen neighborhood.

Their father and homeowner, Pa Cheng Vang, earlier confirmed the deaths of 5-year-old twin daughters Ntshiab Si and Siv Ntshiab and 4-year-old son Mauj Tshau Ntuj.

Vang said over the weekend that a son, 6-year-old Cag Kub Vaj, and daughter, 3-year-old Hnub Qub Vaj, were no longer in critical condition and are showing signs of strength. Their mother also continues to recover at Regions.

St. Paul Mayor Melvin Carter held a moment of silence during Tuesday's city council inauguration ceremony, asking residents to support Vang's family.

"Four of those children, tragically, have passed. Two more children and Ker Lor, who just a few years ago incidentally was an intern in our mayor's office, remain in a fight for their lives," Carter said. "I am grateful for the strength and courage of our St. Paul firefighters, our police officers, paramedics and first responders. It is often stated, and still true, that they are the heroes that race in to help when everyone else is racing out."

Deputy Fire Chief Roy Mokosso said Tuesday that the fire started in a main floor living room.

The bedrooms, presumably where the home's occupants were sleeping, "were in the back of the home above a walk-out level, which would have made it difficult for egress, especially with small children," Mokosso said.

The primary potential way to escape "would have been out the front door, but [that] would have brought occupants through the fire room," he said.

Ernster said the fire's cause remains under investigation, "but nothing has changed. This is still considered a tragic accident."

Alerted by neighbors to the fire around 1:30 a.m., emergency crews arrived at the family's home to find black smoke billowing from the windows and doors. Neighbors were rushing in to help, watching from afar as firefighters performed CPR on Vang's wife and children.

Last week's fire is the deadliest in Minnesota since November 2019, when six deaths were attributed to a blaze at the 25-story Cedar High Apartments in the Cedar-Riverside neighborhood near downtown Minneapolis. One of the victims died months later of COVID-19, with smoke inhalation as a significant factor.

The fire started in a 14th-floor apartment, where an improper door seal, a lack of sprinklers and an antiquated stairwell design allowed flames and smoke to spread rapidly. Investigators suspected an electrical problem or a mishap with a hookah, pipes or lighters caused the fire.

In February 2014, five children died in a blaze in a north Minneapolis home; two of their siblings survived.

Investigators said in a report that they traced the origin of the fire to a "melted mass of material" that was located next to two loveseats in a middle room of the apartment. An attorney for the family said the mass appeared to be a space heater.

Star Tribune staff writer Kyeland Jackson contributed to this report.

Correction: This article has been updated with the correct spellings of surviving children Cag Kub Vaj and Hnub Qub Vaj.