The blast damaged a military commandant's building in the town, which lies in Russia's Leningrad region. St Petersburg television channel 78, citing an unnamed source, reported three deaths. The local outlet 47 News also put the toll at three, relying on emergency-service information. Russian authorities acknowledged casualties but did not provide a confirmed number in the supplied evidence.
Early reporting was fragmented. News.Az cited preliminary local accounts suggesting two service members had died and four people might be trapped under the wreckage. That report stressed that officials had not confirmed either figure. The later three-death total therefore remains a media report rather than a final official toll, and the identities of those killed were not disclosed.
Images circulated by news organizations appeared to show the upper two floors caved in and large piles of debris around the structure. The pictures were not independently verified in the supplied coverage. Reports also warned that remaining sections of the building could collapse further, complicating the effort to reach anyone still inside.
Leningrad regional governor Alexander Drozdenko said soldiers and security forces had been sent to help clear the rubble and rescue potential victims. He said the reason for the collapse was being investigated. Emergency services continued working at the site while authorities assessed the structure's stability.
Russia's Investigative Committee, the agency responsible for major criminal inquiries, opened a case examining a possible violation of fire-safety rules. It said preliminary information established that the incident had caused casualties. The committee did not identify an ignition source or say whether the explosion resulted from an accident, negligence or a deliberate act.
That absence of a verified cause is significant. Russia has experienced attacks on military and civilian infrastructure during its war against Ukraine, while gas leaks have also caused explosions in older buildings. Neither context establishes what happened in Sertolovo, and officials offered no immediate evidence connecting the blast to sabotage or to a gas failure.
The incident occurred as US-brokered talks between Russia and Ukraine began in Geneva, but the supplied evidence showed no link between the negotiations and the explosion. The supported facts remained limited to a destructive blast at a military police site, a reported death toll of at least three, a difficult rescue operation and an official investigation centered initially on fire safety.
