Children and their caretakers walk by the remains of the Flower Branch Apartments fire that killed 7 and left about 100 homeless last month as they get out of school in Silver Spring, MD on Thursday September 01, 2016. (Jabin Botsford/The Washington Post)

Wendy Lopez started fifth grade Monday. On Tuesday, another nightmare.

The school-loving 11-year-old’s days of reading and recess are followed by memories of chaos, screams of despair and the other lingering horrors of having her apartment blown apart by a gas explosion.

“She was happy to be with her friends. She feels safer at school than at home,” said Wendy’s mother, Claudia Loayes, whose family lost everything they owned in last month’s explosion of a Silver Spring apartment complex that killed seven, including one of Wendy’s friends. “But she is still very scared. Any little sound, she says ‘What was that?’ ”

In an interview, Loayes began to cry at the memory of the night she had to drag her daughter to safety through a hellscape of smoky rubble and walls of flame. The catastrophic blast, felt almost two miles away, was only the start of a shock wave that continues to roil the lives of survivors and witnesses, including the youngest ones.

As the start of school introduced a welcome bit of routine almost three weeks after the catastrophe, the signs of trauma are clear in the children involved, both those who fled burning apartments and many more who watched from surrounding buildings as residents jumped from windows and parents dropped children to bystanders below.

A bus drives by the remains of the Flower Branch Apartments fire. (Jabin Botsford/The Washington Post)

“There is a lot of PTSD stuff coming out, kids who have started wetting their beds, kids fighting, kids afraid to sleep at night,” said Elena Reis, the head of Silver Spring’s YMCA Youth and Family Services, which provides mental health services to low-income residents in the neighborhood. “And we know that a lot them who aren’t showing any symptoms now, we’ll be seeing it over time.”

Schools, community groups and county agencies are scrambling to assist the displaced and the traumatized. At New Hampshire Estates Elementary School, administrators provided two dedicated buses to get 15 students to and from their temporary housing. Four extra psychologists, in addition to school counselors, visited the children in classrooms and watched them discreetly at lunch and recess.

One kindergartner built — and then knocked over — a block tower complete with flames and a firefighter, according to Principal Bob Geiger. Another student asked to use the office to call home so he could make sure that his mom was okay.

At nearby Oakview Elementary, the alarms for the usual first-week fire drill were silenced in favor of a pantomime version that wouldn’t trigger any panic. “No lights, no sounds yet,” Principal Jeffrey Cline said. “We’ll work up to that.”

An emotional peak came Thursday, when the mother of one of the children who died in the blast showed up at New Hampshire Estates and asked to see her 8-year-old son’s classroom, according to Reis, whose agency works with a counseling program in the school.

“His teacher was crying, too. It was very sad,” she said. “This is all going to take a long time.”

The explosion, which investigators said was caused by a rapid gas leak in a basement utility room, injured more than 30 people and collapsed four floors of apartments. It took more than 100 firefighters to contain the blaze, and the site remains a scene of stark devastation.

Loayes, a hotel housekeeper, said she, her daughter and a toddler she was watching for a friend were in bed but awake in their second-floor apartment that night when a boom shook the walls. Seconds later, there were cries of “Fire! Fire! Get out!” Loayes, who thought an earthquake had struck, gathered the children and bolted to the front door.

But the front door was gone. So were the hallway stairs.

Wendy panicked, pulled away and ran back into the apartment. The flames were rising on all sides now. Loayes said she doesn’t know if it was the rubble around her legs or terror that paralyzed her.

“I couldn’t move. I just screamed, ‘Wendy! Wendy!’ ” she said, crying at the memory. “I prayed as I’ve never prayed before.”

The flames were surrounding her when she finally heard Wendy call out that she was with Renaldo, Loayes’s partner. Loayes, still holding the toddler, scrambled down the debris pile and, finally, into the clear. Wendy and others from the building gathered outside.

But two boys, including the 8-year-old who was Wendy’s playmate, never made it out of the basement. One of their mothers stood in the light of the fire screaming for her child.

“Every time we go by there, I hear those screams,” said Loayes. Her family is living in a temporary apartment across the street. Their view of the blast site — where their former home is a gaping crater — is screened by another building.

She is among many residents who walk out of their way to shield their kids from the blackened, jagged ruins. One woman keeps her blinds closed day and night.

Many of those still living in the complex, even in undamaged buildings, remain on edge. Christy Canjura, 16, a junior and cross-country runner at Montgomery Blair High School, said firetrucks have come back three times since the explosion after rumors of another gas leak. She has evacuated each time.

“You get anxious all over again,” said Canjura, who lives in the complex with her mother. “We’re still stuck here, basically like we’re waiting for another explosion.”

Randy Carbajal, a painter from El Salvador, said his three children have refused to return to their old apartment, which is adjacent to the building that blew up. The family has been crowded in with Carbajal’s brother and sister-in-law, returning to their old home only once to retrieve clothes. The children, once avid cooks, are unnerved by the gas stove. “They are afraid to go into their own kitchen,” he said.

Elba Rivas has been hearing similar stories since the day after the blast. A therapist at the Mary Center, a health nonprofit organization a block from the blast site, Rivas said her first clients were openly traumatized. Lately, parents are bringing children in with upset stomachs, difficulty breathing and other medical complaints. Doctors at the center have quickly referred them to the counseling staff.

“It’s beginning to show up as physical symptoms,” she said.

Maritza Quintanilla, who looked out after the explosion to see clothes flying through the air followed by columns of fire, has been taking her two boys for counseling at the Mary Center once a week since the incident. Although they still struggle at night — Andy, 5, trembles at every siren and won’t sleep alone — they have begun to ride their bikes and play outside again.

Still, “I would like to move to a house,” said Gerardo, 12. “I think it will be safer in a house.”

Rivas and other counselors lamented that more families aren’t coming in for therapy. They say mental health services can be a hard sell in immigrant neighborhoods, where counseling may not have been commonly accepted in their home countries. And many are still overwhelmed with putting their daily lives back together.

“Right now, they are still in survival mode, figuring out where they are living and getting the kids to school,” Reis said. “If a mom has an hour to come in, she may need to use it to go through clothes for her children.”

Alma Couverthie, director of organizing at CASA de Maryland, said she has been discouraged by the number of victims coming in for other assistance who are clearly in need of emotional help.

“My concern is when I ask them, ‘Are you getting any therapy?’ The answer is ‘No, I don’t have anybody,’ ” Couverthie said. “The counselors in the schools are great, but that may be one counselor for hundreds of kids.”

Loayes, Wendy’s mom, said she hadn’t seen a therapist, nor had her daughter, even though both were still clearly unnerved by the nightmarish events.

“I have been asking God to help her,” Loayes said of Wendy. “I tell her that God has given us another chance and we’re never going to go through that again.”

Luz Lazo contributed to this report.