By Elizabeth Wolfe and Rob Frehse, CNN
(CNN) — The FBI and local authorities are examining the cause of a home explosion that erupted in northern Virginia on Monday night as police were trying to execute a search warrant, as well as “concerning” social media posts allegedly made by a suspect who investigators believe was barricaded inside, authorities said.
The suspect, 56-year-old James Yoo, is presumed to be dead after human remains were found at the scene of the incinerated home in Arlington, just 5 miles southwest of the nation’s capital, Arlington County Police Chief Andy Penn said Tuesday.
Medical examiners will work to positively identify the remains and determine the cause and manner of death, he said.
When the explosion happened, police were trying to serve a search warrant at the duplex where Yoo lived over suspicions that he had fired more than 30 flare gun rounds from the home into the surrounding neighborhood earlier in the day, police said. The warrant was obtained to secure any weapons in the home and “ensure there would be no ongoing threat to the community,” he said.
The explosion led to evacuations at several homes, officials initially said. The county’s deputy manager for public safety, Aaron Miller, said Tuesday that 10 households were impacted by the incident and the county has been helping some of them by providing shelter, toiletries and other necessities. It’s unclear to what extent the households were impacted.
Since the explosion, investigators have uncovered “concerning social media posts” allegedly made by Yoo, the police chief said.
LinkedIn posts from Yoo’s account espouse rambling and at times incoherent conspiracy theories against government officials, law enforcement, media outlets and, in one post on Friday, his neighbors whom the post accuses of being spies and collecting his information for unnamed handlers.
The explosion and the suspect are being investigated by the Arlington County Fire Department and a team of northern Virginia law enforcement, with assistance from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives, Penn said.
Here’s what else we know about the incident and the suspect so far.
Suspect had been calling and writing to FBI for years, authorities say
Both the FBI and Arlington police said Tuesday that they had previously interacted with Yoo, but none of the encounters led authorities to open investigations.
Yoo had communicated with the FBI for several years through phone calls, letters and online tips, said David Sundberg, assistant director in charge of the agency’s Washington, DC, field office.
“I would characterize these communications as primarily complaints about alleged frauds he believed were perpetrated against him,” Sundberg said. The communications did not prompt the agency to open any investigations, he added.
Prior to Monday, Arlington police had documented only two calls for service at the address over the past few years, both for complaints about loud noise, according to Penn.
How the explosion unfolded
Officers first came to the home in Arlington’s Bluemont neighborhood shortly before 5 p.m. Monday due to a report of possible shots fired near the residence, police said.
Further investigation revealed the suspect had discharged a flare gun from the home more than 30 times into the surrounding neighborhood, police said.
“Officers attempted to engage with the suspect without success,” Penn, the police chief, said Tuesday. “A search warrant was ultimately obtained to allow our officers to secure any weapons to ensure there would be no ongoing threat to the community.”
Police tried to communicate with Yoo by phone and through loudspeakers, but he wouldn’t respond and remained barricaded inside, according to police.
As an emergency response team breached the front door, the suspect fired several rounds, from what is believed to have been a firearm, inside the home, Penn said.
Officers continued trying to engage with the suspect and bring him into custody but could not locate the source of the suspected gunfire, Penn said. They then began to deploy “non-flammable, less lethal chemical munitions to multiple areas within the residence where the suspect was believed to be hiding” to get the suspect to surrender, the chief said.
Sometime afterward, around 8:25 p.m., the home exploded, police said.
Video taken by a witness shows law enforcement vehicles surrounding a multi-story home when an explosion sends a plume of flames, embers and smoke into the air and debris raining down into the street. The force of the explosion blew the roof and several walls apart, causing the structure to collapse.
Firefighters worked into early Tuesday to extinguish the blaze, said Jason Jenkins, assistant chief of the Arlington County Fire Department.
Other residents of the duplex where Yoo lived were evacuated before the explosion, Penn said. Fire personnel had also turned off the gas supply to the home before the explosion happened, according to Jenkins.
“Thankfully, there were no serious injuries to any officers, other public safety officials or community members,” Penn said.
Neighbors rattled by powerful blast
The explosion reverberated throughout the neighborhood Monday night, stunning many residents.
Resident Davin Mitchell told CNN affiliate WJLA that he was watching the law enforcement activity around the home when it erupted. The force of the blast threw him back several feet, he said.
“It was just shell-shocking,” Mitchell said. “It rocked you to your core.”
Earlier that day, Mitchell said he saw about 20 flares being fired in the neighborhood and hitting the street.
Another neighborhood resident, Emily Saxon, said she was lying on her couch and “physically recoiled” when the explosion shook her home.
“I had no idea what it was. I quite literally thought maybe there was a car that ran through my living room because it was that abrupt,” Saxon told WJLA.
Police have said there is no ongoing threat to the community.
CNN’s Melissa Alonso, Holmes Lybrand, Hannah Rabinowitz, Amanda Jackson and Sara Smart contributed to this report.
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