Arlington, Virginia, officers were investigating shots fired and executing a search warrant when a house exploded.
No deaths have been reported, and the suspect's status in the residence during the explosion is unknown.
Shots fired about 4:45 p.m. were later identified as flare gun firing. Next, a search warrant was issued for the home.
The suspect shot several rounds inside the home when police tried to execute the search warrant.
Flames and power disruptions followed the explosion. Stretcher units were near the site, suggesting a major incident.
Authorities don't know if the suspect fired flare gun or other shots. Early evidence of duplex occupants is inconclusive.
The explosion occurred in north Arlington suburb Bluemont. After hearing a massive boom, residents saw power outages and flames.
The cause of the explosion remains unknown as firefighters combat the fire.