Ivan Sekretarev / AP / TASS Two people were hospitalized with serious injuries after a helicopter accidentally fired on bystanders at the Zapad 2017 military exercises, the online news portal 66.ru cited a source as saying on Tuesday.

The week-long drills in Western Russia and neighboring Belarus kicked off last week, with around 13,000 troops, hundreds of tanks, aircraft, warships and other military hardware participating.

The incident reportedly took place at the Luzhsky range near St. Petersburg either on Monday or Sunday. President Vladimir Putin visited the range on Monday.

The unnamed source told 66.ru that there appeared to have been a technical glitch on board “and the missiles blasted off on their own.”

“At least two cars burned down, two people were seriously injured, they are now hospitalized,” the source said. “The victims were most likely journalists.”

The Russian Defense Ministry said two attack helicopters simulated aerial reconnaissance and close air support missions on Monday as part of Zapad 2017.

Video footage accompanying the news report appears to show one of the helicopters misfiring *a surface-to-air missile in the direction of camera crews.

*The Defense Ministry’s press service denied that the incident took place on Monday, saying “all social media messages about ‘rounds on a crowd of journalists,’ ‘a large number of seriously wounded’ are either a deliberate provocation or someone’s personal stupidity.”

*“[Video footage] recorded an event that occurred at another time, when army aviation helicopter crews practiced ground attacks as part of a tactical exercise.”

*The press service said one of the helicopters engaged a wrong target, adding that one truck was damaged and no people were hurt from a self-propelled rocket hit.