The Philippines has temporarily blocked gaming app Gorebox after an initial investigation found that a teenage suspect in a rare school shooting had been playing the game.
Three students were killed and 20 others wounded after two suspects - aged 15 and 14 - allegedly fired handguns inside a classroom in Tacloban, south-east of Manila, on Monday.
Police said the 14-year-old was a player of Gorebox, a game where players can "obliterate anything [they] desire" and "engage in brutal combat with an extensive arsenal of weapons and explosives", according to its Google Play listing.
"We cannot ignore possible online influences that may have contributed to this tragic incident," the country's cyber-security agency said.
"Temporarily blocking the game will allow authorities to conduct a thorough assessment into whether the platform played any role in the actions of the suspects," said Aboy Paraiso, an undersecretary at the Cybercrime Investigation and Co-ordinating Centre.
BBC News has contacted Gorebox's maker, Germany's F2Games, for comment. Scientific studies have not found a direct link between video games and violent behaviour.
Gorebox is a first-person shooter video game that can be played as solo or online multiplayer. The International Age Rating Coalition gave it an R18 rating due to extremely violent, explicit, and unrestrictive gameplay.
Mass shootings are rare in the Philippines, though gun-related crimes are not uncommon and the most sensational cases are staples of early evening newscasts.
What was unusual this time round was that the suspects were minors.
Akbayan party-list congressman Chel Diokno called for stiffer penalties for those who allow minors access to firearms.
The worst mass shooting in recent Philippine history happened in November 2009, when a town mayor in the southern province of Maguindanao shot dead 58 people, mostly journalists, who were travelling with the convoy of a political rival.
Late on Tuesday, police filed murder charges against the 15-year-old suspect.
The 14-year-old suspect who allegedly played Gorebox is too young to be charged under Philippine law.
He appeared to have been "heavily influenced" by online content, said Allan Rae Co, spokesman of the Philippine National Police.
The boy had also been posting violent content online, he added.
Police said the 9mm pistol the 14-year-old is alleged to have fired belonged to his aunt, a policewoman who was suspended from duty after the shooting. The 15-year-old's .38 was registered to his grandfather's security agency.
According to the preliminary investigation, the suspects claimed they were bullied in school.
Before Monday's shooting at the San Jose National High School, Co said the two boys had holed themselves up in the bathroom.
"All indications point to the fact that it was planned," Co said.
