The body of a third victim was found Friday at a Silver Spring apartment complex that was severely damaged in an explosion Wednesday night, Montgomery County police said.

Authorities had said earlier Friday that more bodies were probably buried in the rubble at the complex, where the first two victims were found. They said recovery efforts and the investigation were hindered by the structure’s instability and an intense heat wave.

Officials from local and federal agencies, including the Bureau of Alcohol, Tobacco, Firearms and Explosives, said they did not know as of Friday how many people were still missing. Nor could they identify the first two victims whose bodies were recovered, both of which apparently were burned beyond recognition.

Although Montgomery County Executive Isiah Leggett (D) has said natural gas was probably involved in the blast, ATF officials said the agency’s top fire and explosives experts were assisting local authorities to try to determine the cause.

“It’s been a very challenging incident for us not only in terms of the hot weather, but the building still presents as a collapse hazard,” said David Steckel, the county’s acting fire chief, whose firefighters slowly and carefully searched the rubble with cadaver dogs.

People displaced from a fire that killed two people and injured dozens at an apartment complex in Silver Spring find shelter and assistance from their neighbors. (Whitney Shefte/The Washington Post)

In addition to the three known deaths, 34 people were injured in the explosion, which was so powerful that it blew doors and debris hundreds of feet into the air and nearly leveled the building.

Dozens of families in the working-class and primarily Spanish-speaking complex lost everything.

Representatives from local nonprofit groups, faith groups and county agencies began coordinating a response Friday, aided by government officials from Honduras, Mexico, El Salvador and Guatemala.

“This is going to take awhile,” said Gracie Rivera-Oven of the Latino Health Initiative, who described arriving at the scene and watching people walk around shoeless and dazed.

Many residents fled their homes with nothing, leaving behind wallets, car keys and other possessions — “everything they had built in this country,” as one official put it this week.

About 50 people spent Thursday night at a nearby recreation center, county officials said. Early Friday morning, one woman with a bruised and bandaged arm slipped into a restroom, and other people picked up toothbrushes and other toiletries from a pile of donations on a table nearby.

Andre Guzman, 45, a native of Guatemala, had been working in construction to support his family back home. Now he had nothing but the quarter in his pocket.

“I need an apartment,” he said. “I need work.” But before he can work, he needs new boots. He lost his in the fire.

Twenty-four units were destroyed or rendered uninhabitable, according to the county. But many of those units housed more than one family, so there are up to 60 households in need of shelter.

Mary Anderson, spokeswoman for Montgomery’s Department of Health and Human Services, said officials are identifying the size of each household so they can match it with an appropriate apartment. Nonprofit and for-profit developers have come forward offering units, she said.

“We want to move people from the shelter into permanent housing” rather than asking them to hopscotch from one temporary home to another, she said. “Ideally, that would be in the next few days. Realistically, it might take a little longer.”

Uma Ahluwalia, the agency’s director, urged sympathizers to send cash donations or gift cards, saying officials had already received more in-kind gifts than they can handle. “We do not need any goods,” she said. “No food, no water, no diapers at this time. We will need them later.”

The explosion has raised questions about living conditions in the 60-year-old apartment complex, which like other apartment buildings in the county is inspected every three years.

The most recent inspection, in 2013, turned up more than 500 violations, according to county records. Some were trivial — ceiling fans without pull strings — but others signaled hazardous conditions, including overcrowding and inoperative smoke detectors. Records indicate that the violations were fixed by August 2013. Code enforcement officials did not respond to calls or emails Friday.

Kay Apartment Communities, which manages the complex, Flower Branch Apartments, did not respond to questions about living conditions. The company said in an email that those who could respond were busy helping those left homeless by the explosion.

Lt. Gov. Boyd Rutherford (R) will visit the scene of the fire Saturday morning and meet with Leggett, said a spokesman for Gov. Larry Hogan (R). Hogan offered condolences to the families displaced by the fire.

“We will continue to work with local officials and County Executive Leggett, and provide the needed resources to keep residents safe and help to ensure no further damage or loss of life,” Hogan said in a Facebook post Thursday evening.

The psychological wounds will prove more difficult.

Mary’s Center, a clinic one block from the destroyed apartments, has seen a stream of displaced people seeking mental-health counseling since the explosion. Isabel Sosa showed up there Friday worried about her 10-year-old daughter, Mercy Vega.

Their family lives behind the destroyed building and knows some of the affected families. The explosion jolted them awake, Sosa said. Stepping outside, they stared in shock at the destruction.

Since then, Mercy hasn’t slept much, her mother said.

“I’m really worried about her,” Sosa said in Spanish. “People say that she should cry, or get angry or talk, but she hasn’t done any of that.”

The little girl sat in the lobby waiting to see a counselor.

“I’m afraid this will happen again, but in my building,” she said, staring down at her hands.

Bill Turque, Luz Lazo, Lynh Bui, Fenit Nirappil and Martin Weil contributed to this report.