Flames rise from a vehicle following a fatal crash Sunday in Hyattsville, Md., just northeast of Washington. (Steve Ramsey/AP)

People had often arrived a little late for the services that Pastor Jose Angel Santos Jimenez leads in Riverdale.

But on Sunday, after the hymns and church announcements, almost half of the congregation still had not appeared in the modest meeting room with straight-backed chairs and heavy patterned carpet where they worship.

The pastor opened his Bible, preparing to preach to the two dozen faithful on hand.

His cellphone rang.

And before he had a chance to speak, he had to listen — to someone from the local children’s hospital telling him that some of his missing congregants were arriving for medical attention. The news was “bastante fuerte” — “very hard” to take.

Pastor Jose Angel Santos Jimenez of the Iglesia Ministerio de Dios Unidos in Riverdale, Md., visits the site of a crash between a church van and a pickup truck, which left four dead and 13 injured. (Arelis Hernandez/The Washington Post)

The worshipers traveling by church van from Georgia Avenue in the District would not make it. A pickup truck had slammed into the van carrying 16 to the Sunday evening service. The crash exploded into fiery wreckage about four miles from the church on Kenilworth Avenue in Prince George’s County.

Four died, and 13 were injured, including a woman who was eight months pregnant and lost the fetus.

“It was worse than anything I could’ve thought,” said Santos Jimenez, pastor of the Iglesia Ministerio de Dios Unidos. “I’m not a man who cries. I’m strong. But I haven’t stopped.”

Authorities say a pickup truck driver fled the scene of an earlier rear-end collision on Chillum Road and lost control of his truck about 5 p.m. before crossing the double yellow line and hitting the oncoming van.

The truck may have caught fire as a result of the first crash, authorities said, and caused an explosion when it struck the van.

“I’m just looking at the whole front lawn of this house, and there’s just bodies laying there,” said Bill Corrigan, volunteer chief of the College Park Fire and EMS Station, who coordinated the work of the 60 emergency responders from around the region at the scene. “You could see in the guys’ faces that they had that look like, ‘What the hell just happened?’ ”

Prince George’s officials said the crash was one of the most horrific the county has seen. And the aftermath of the crash has devastated the congregation of roughly 45 people, many of whom are immigrants from El Salvador and Honduras.

The site where a crash Sunday night between a pickup truck and a van left three adults and a child dead in Prince George's County. (Matt Zapotosky/The Washington Post)

The dead include 6-year-old Stanley Gomez, a girl whose mother, Sandra Gomez, was injured in the crash and also had an injured infant sent to a hospital. Others who died in the crash were the driver of the truck and an elderly couple in the van.

Although Sandra Gomez has discussed her loss, as of Monday evening police had not publicly identified any of the victims as they continued to confirm identities and notify relatives. Authorities are also investigating the cause of the initial crash and are working to determine whether passengers were wearing seat belts or children were fastened into safety seats.

In addition to the four dead at the scene, 13 people — including children as young as 6 months old — who were in the van were rushed to hospitals.

The pregnant woman, who underwent emergency surgery, is married to the driver of the van, and the couple already have two children, both of whom were injured in the wreck. The couple’s third child was due in less than two months, and they already had chosen the name Isaias.

The church, formed almost two years ago when it operated out of a home, now meets Sunday night in a Riverdale office building. The church provides van service to transport congregants from their apartments near the intersection of Georgia and Missouri avenues in Northwest Washington.

On Monday, the pastor’s eyes reddened and he grimaced. He tried to push down the emotion, but a tear escaped as he described what happened a day earlier.

His wife, Oneida Santos Jimenez, said the members who were there at the service immediately began to cry out to God, pray and wail.

“It was strange for them not to have arrived that we already had a bad feeling,” she said. “We knew something was wrong.”

Leydi Lizama, 39, said she was on her way to the bank when she saw a pickup truck crash into the bumper of a brown car. The impact surprised her: The car’s bumper, Lizama said, was significantly pushed in. But what happened next was even more startling: The truck, which had caught fire, sped off, Lizama said.

“He hit someone,” Lizama said, “and tried to run away.”

Lizama said she continued up the road, and a few minutes later, she saw the speeding truck barrel into the van. She said her view of the van was obscured — and she didn’t want to get out of her car because her daughter was inside — but she saw the truck’s driver apparently trapped inside his vehicle.

“He was screaming,” Lizama said. “He say, ‘Help me! Help me!’ ”

The collision filled the air with the smell of gas and loud booms, causing neighbors in the community near the West Hyattsville Metro station to come running from their houses with fire extinguishers and a garden hose to try to quell the frames.

Other neighbors, including L’Shauntee Robertson, 35, rushed over to pull bodies out of the wreckage and comfort the injured.

“It was something out of a movie,” said Robertson, who lives in the area and rushed to aid the injured. “There was so much excruciating pain and grief in the air.”

She said she ran to a screaming girl who was covered in blood, trying to comfort her until she could be taken to a hospital. Next to her, a man arrived to do the same, cradling the head of another girl — her face burned and barely recognizable — in his hands.

“I had already counted three,” Robertson said of the dead who surrounded her. There was “the little girl, the man and someone on the other side of the truck in the yard. I kept thinking, ‘No more. Please, no more.’ ”

Inside the church, after the call, the pastor announced that there had been an accident, and services ended.

He went to the scene. His church members had already been removed and taken to hospitals — several of them, so as not to overload any one with all of the severe injuries that needed treatment.

At least three large fire departments from the region and two medical helicopters responded to the crash, authorities said.

At the crash scene Monday morning, black char, triage tags, and the blue and purple gloves of emergency responders stood as a reminder of what happened. A Spanish-language religious CD was in the street, not far from a garden hose, still dripping water, in the adjacent yard.

Witnesses to the crash recalled a boom and tall spires of flame.

Wayne Sims lives about three blocks from the site. As he was pulling a trash bin into the street, he heard three booms. Then, screams.

He hopped into his car with a neighbor and headed toward the rising black column of smoke.

When he arrived, the former Marine saw a scene that rivaled his days in the service, he said.

“It was a blazing inferno,” said Sims, 49. “It was one of the most horrific scenes I’ve seen in a while.”

On Monday evening, after visiting church members at the hospital, Santos Jimenez brought his brother, wife and sister-in-law to the spot where nearly half of his congregation had been injured or killed.

They walked slowly past the strewn car parts, a child’s torn pants amid leaves, the responders’ gloves.

As they walked, they nudged items with their toes until it became too much for the pastor’s wife. Her husband and family wrapped her in an embrace and prayed, their words harmonizing as they asked God for strength.

Doris Medrano tried to be strong while her sister-in-law cried. As the prayer ended, Medrano looked up the road to where investigators had marked the path of the truck.

She bent over, grabbed her knees and sobbed.

Her tears darkened the charred pavement beneath her.

Dana Hedgpeth, Pamela Constable and Jennifer Jenkins contributed to this report.