ATCHISON, Kan. — Authorities say three young men were killed in a thunderous explosion at a Kansas grain elevator, and recovery efforts for three other people presumed dead are being hampered by the damage.

The explosion occurred Saturday night at a Bartlett Grain Co. elevator in Atchison, about 50 miles northwest of Kansas City. The blast was so powerful that it shook the ground in neighboring Missouri.

Local authorities identified those killed late Sunday as 20-year-old Chad Roberts, 21-year-old Ryan Federinko and 24-year-old John Burke.

The company says one worker and two grain inspectors also are presumed dead. Their names haven't been released.

Crews temporarily suspended their search for the three earlier Sunday because of safety concerns inside the heavily damaged elevator. The search is expected to resume Monday morning.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

Crews suspended their search Sunday for three people missing after a thunderous explosion at a Kansas grain elevator killed three workers and hospitalized two others with severe burns.

Officials with the company that owns and operates the elevator said in a statement that they know the location of those who are missing and will resume the search at some point. They have brought an engineer to the scene to help develop a plan on how to continue the recovery effort.

The blast, which shook the ground so hard that it was felt into neighboring Missouri, is a harrowing reminder of the dangers workers face inside elevators brimming with highly combustible grain dust at the end of the harvest season.

The explosion Saturday night at the elevator in Atchison, about 50 miles northwest of Kansas City, sent 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 the one of its concrete silos.

Bartlett Grain Co. officials decided to temporarily halt the search for the three missing people – one worker and two grain inspectors_ because it was unsafe to be inside the facility, said Atchison City Manager Trey Cocking. Smoke could still be seen billowing from the top, and officials were fearful the building could fall on top of rescue crews.

"It's a fairly dangerous situation. We don't feel comfortable putting fire crews in," Cocking said.

He said crews had not given up hope that they would find the remaining three alive, although the search was now considered a recovery effort. The victims' names had not been released by Bartlett Grain as of Sunday evening.

One of 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."

Rob Nohr, an engineer from Yankton, S.D., hired by Bartlett Grain, was at the scene Sunday night with federal safety investigators assessing the situation and coming up with the next steps of the recovery plan. Grain company officials said Nohr is an expert in helping investigate such accidents.

Bartlett Grain President Bill Fellows said in a statement that workers were loading a train with corn when the explosion occurred, but the cause was not immediately known.

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. Just last year, there were grain explosions or fires in several states including In Nebraska, Illinois, Ohio, South Dakota and Louisiana. None were fatal, but several sent workers scrambling and one in Toledo, Ohio in September 2010 forced people to evacuate from a nearby mobile home park.

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.

He said the industry as a whole has increased awareness of the dangers since a number of elevator explosions along the Gulf in the 1970s.

"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.

The two people injured in the explosion were taken to the burn unit at University of Kansas Hospital in Kansas City, Kan., hospital spokesman Dennis McCulloch said. One was listed in critical condition Sunday evening and the other was in serious condition, he said.

Cocking said four other people, including one woman, escaped without injuries. No names were being released pending notification of families.

Paul Moccia, who lives about a half mile from the grain elevator, said the explosion shook his house and lights flickered across his neighborhood for about 30 seconds.

"It was extremely loud. It was kind of like to me a double whomp, – a bomp bomp. It reverberated, and kind of echoed down through the valley. ... kind of like a shock wave," said Moccia, 57. "Everybody came outside. Neighbors were trying to figure out what was going on. It was quite a thump."

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