NEW YORK — Two infernos raged across Brooklyn on Sunday, one of them leaving three children clinging to life after their parents left them unsupervised inside an 11th-floor apartment, authorities said.

The first fire broke out inside the Van Dyke Houses on Livonia Avenue near Powell Street in Brownsville around 11 a.m., according to FDNY Chief of Department John Hodgens.

Firefighters entered the smoldering unit to discover the unconscious bodies of children ages 8, 5 and 4, Hodgens said.

Rescuers had to crawl through the smoke-filled apartment to extract the injured kids and immediately attempted to resuscitate them before handing them off to paramedics who performed more advanced, life-saving maneuvers, according to the fire chief.

It took firefighters 12 minutes to reach the scene, ascend the tower and pull out the children, said Hodgens, who credited their survival to the rapid response.

“They had to go to work quickly, get them out, and get them over to EMS and paramedics,” he said. “That’s why they’re alive today.”

Police are investigating why the children were left to fend for themselves inside the Brownsville housing complex, and investigators have brought in their father for questioning, according to a spokeswoman.

A neighbor said the children’s mother left her kids with their father as she went to work, and that the dad had gone to grab food when the fire broke out.

“Never leave kids alone. It’s terrible. Three kids, one is four years old!” said Jose Nieves, who lives in a neighboring building at the Van Dyke Houses.

Another resident said he worried that the long minutes that children spent unconscious would lead to brain damage.

“They were unconscious so long,” said Jason Johnson, who lives on the 12th floor of the building where the fire broke out. “Brain cells die. Hopefully, that won’t happen.”

“They were too young,” he added.

No charges had been filed as of Sunday evening, the NYPD spokeswoman said.

Sunday’s second fire erupted inside a commercial building on Lee Avenue near Williamsburg Street East shortly before noon, injuring 10 firefighters, according to Hodgens.

The inferno spread quickly through an attic shared by nine small businesses, including a chocolate shop and grill, all of which were damaged in the blaze, the chief said.

The businesses were closed for the weekend, and an army of 200 firefighters struggled to bust through roll-down gates guarding the sealed shops in order to pour water on the fire within, according to Hodgens.

“We had to force our way into every store,” he said. “Nine stores — all had closed gates.”

One of the 10 injured firefighters was listed in critical condition due to his “altered mental status,” according to FDNY Commissioner Laura Kavanagh, who said the smoke eater was given medicine for carbon monoxide poisoning.

No civilians were injured in the Williamsburg fire, officials said.