Updated

Distraught and anxious family members gathered Monday outside a Kansas grain elevator as authorities searched for three more people likely killed in a weekend blast that left three others dead.

Lynn and Patty Field, of Atchison, said their 21-year-old son, Curtis Field, was among those still officially considered missing. They said the two others were state grain inspectors. Crews were working to stabilize the debris Monday in the Bartlett Grain Co. facility in Atchison, about 50 miles northwest of Kansas City.

"I don't know what else to do," Patty Field said. Then, starting to cry, she added, "I just want him home — I mean, out of there. I want him home, but I know he's not coming home."

Unstable concrete, hanging steel beams and other damage caused by a powerful explosion that ripped through the elevator were complicating efforts to find the missing people. The bodies of three other workers were recovered after the Saturday blast, and two people are hospitalized with severe burns.

The explosion was a harrowing reminder of the dangers workers face inside elevators brimming with highly combustible grain dust at the end of harvest season. The blast fired an orange fireball into the night sky, shot off a chunk of the grain distribution building directly above the elevator and blew a large hole in the side of a concrete silo.

The search for three people presumed dead was temporarily halted Sunday because of fears that the building could fall on rescuers. Local officials met with victims' families to explain why crews pulled back, but understood they wanted their loved ones found, Atchison City Manager Trey Cocking said.

The three Bartlett workers whose bodies have been recovered were identified as Chad Roberts, 20; Ryan Federinko, 21; and John Burke, 24.

Roberts planned to get married Nov. 19 and take a honeymoon cruise to the Bahamas, said Alicia Cobleigh, his fiancée. She said he liked to hunt and fish and took her fishing. They'd met in high school.

"He was fun, and he couldn't wait to be a husband and a dad," she said "We actually bought a house in April and remodeled it."

Family members and friends turned the sign outside the elevator into a memorial for the workers. A sweatshirt with Federinko's name written on it in marker also was marked, "Why!"

Among the missing was Travis Keil, a war veteran who had served as a site inspector for 16 years. His parents, Gary and Ramona Keil, drove from Salina to Atchison to wait with his three children — ages 8, 12 and 15 — as crews searched.

"We have all our prayers working for him," Gary Keil said. "It's a parent's worst nightmare to go through this."

Bartlett Grain President Bill Fellows said in a statement that workers were loading a train with corn when the explosion occurred, but the cause of the explosion remained unclear. The company brought in a South Dakota-based engineer with expertise in such accidents to help federal safety investigators at the scene.

Farmers take their grain to grain elevators after harvest to store it before it is marketed or sold. The Bartlett grain bin is a large, concrete structure for elevating, storing, discharging, and sometimes processing grain.

Over the past four decades, there have more than 600 explosions at grain elevators, killing more than 250 people and injuring more than 1,000, according to the Occupational Safety and Health Administration. Last year, there were non-fatal grain explosions or fires in several states including Nebraska, Illinois, Ohio, South Dakota and Louisiana.

When grain is handled at elevators, it creates dust that floats around inside the storage facility. The finer the grain dust particles, the greater its volatility. Typically, something — perhaps sparks from equipment or a cigarette — ignites the dust. That sends a pressure wave that detonates the rest of the floating dust in the facility.

Fireballs are a common feature of grain dust explosions, where intense heat from the blast can reach 1,500 to 2,000 degrees.

Dust from corn is among the most dangerous. Most dust explosions happen in late summer and early fall when old, dried grain is being cleaned out of elevators in preparation for the harvest. Freshly harvested corn is less explosive because its wetter.

The Atchison elevator, which is federally licensed to handle up to 1.18 million bushels, is among roughly 850-plus elevators in Kansas. The state is now winding up its fall harvest of corn, sorghum and soybeans.

OSHA has expanded its inspections and efforts to control volatile grain dust in Kansas elevators since an explosion in 1998 at DeBruce Grain, Inc.'s facility in Haysville, which killed seven workers and injured 10 others, said Tom Tunnell, executive director of the Kansas Grain and Feed Association, the industry group representing Kansas grain elevators.

"If ever an industry is as well trained, it is ours. We understand dust is an explosive agent and our members work hard to control it," Tunnell said Sunday.

The Atchison facility where the blast occurred has not been cited for any violations in the last 10 years, according to OSHA data, though Bartlett Grain Co. was cited after two people died in separate incidents at two of its other facilities. Neither of those fatalities involved explosions at grain elevators.

In 2007, a Bartlett Grain maintenance employee died in a fall from a work platform at the company's facility in St. Joseph, Mo. In 2004, another employee died while operating a lift that fell backward at a company site in Kansas City, Mo.

"The industry has had a good record — except for a few of this type — considering the billions and billions of bushels of grain handled," Tunnell said.

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Hegeman reported from Wichita, Kan. Associated Press Writer John Hanna contributed to this report from Atchison, Kan., and Maria Sudekum Fisher, from Kansas City, Mo.