But she still has no news of his fate.
"I learned what happened on television -- and even now no one has contacted me," she said.
The mother, who appeared to be in shock, said 18-year-old Liu Zhiqiao had been with the Fifth Squadron of the Tianjin Port Fire Department for just over half a year. He remained missing on Saturday.
She tried to attend a news conference at the Tianjin Hotel on Saturday morning regarding the explosions that killed at least 112 people in this northern Chinese city.
But, along with family members of other missing firefighters, she was barred by hotel staff from entering the room where the news conference was taking place.
Their screams alerted journalists to their presence, and cameramen jostled for position to video whatever they could through the gaps between closed doors, as hotel staff stood guard and refused to let people out of the room.
The three officials on stage appeared unfazed, reassuring the public about the safety of the area amid lingering concerns over toxins in the air and water supply.
Many firefighters among victims
The plight of firefighters -- especially the contractors -- has gripped the nation of 1.3 billion people following the incident, with government officials calling it the deadliest disaster for the profession since the Communist takeover in 1949.
As of Sunday morning, 50 people had been rescued, but 95 people remained missing, including 85 firefighters, Tianjin government spokesman Gong Jiansheng said.
At least 21 firefighters had been killed battling the fire, he said.
Gong said the latest death toll included contract firefighters, who battle fires just as their official counterparts do -- but who do not enjoy the same military status or benefits.
Journalists from CNN and other news organizations tracked down the family members in a cramped elevator lobby, forcing a dozen or so police back into a stairwell.
Looking desperate, the group included the parents of two contract firefighters from neighboring Hebei province.
Liu Huan, who lives in the same village as Liu Runwen -- who is no relation -- said his oldest son, Liu Chuntao, 22, joined the same squadron as Liu Runwen's son about four months ago.
"Even if they say our children have died, they should treat our kids the same way as they do official firefighters," Liu said.
"Whether they live or die, they deserve equal treatment."
State media, including national broadcaster CCTV, interviewed some of the first firefighters on the scene, who said that they sprayed water on the fire.
That revelation has prompted many to question whether the firefighters' initial response -- trying to put out a chemical fire with water -- caused the subsequent explosion, as some chemicals stored in the facility are known to react violently with water.
Although officials have dodged such questions at news conferences in the past few days, critics have called China's firefighters poorly equipped and inadequately trained, especially those contractors who are often recruited from the impoverished countryside.
As more than 1,000 firefighters continue to battle the blaze around the clock, their comrades who lost their lives -- the youngest was only 17 years old -- are being honored across state and social media.
Many media outlets and fire departments have grayed their profile images on social media sites such as Weibo
as a mark of respect.
And the nation rejoiced Friday when a 19-year-old firefighter was found alive after having been missing for more than 31 hours.
Liu, the mother of the teenage contractor firefighter who remained unaccounted for, prays for the same miracle.
"I just want my child back," she kept telling reporters.