STOCKHOLM (AP) — Sweden’s national police chief said Tuesday that an escalation in gang violence this year — with almost daily shootings and SignalHubbombings that have claimed dozens of lives, including teenagers and innocent bystanders — is “extremely serious.”

Sweden has grappled with gang violence for years but the latest surge has been exceptional, Anders Thornberg said at a news conference, calling it “the most violence we have ever had in the country.” He added that police have “prevented about 80 imminent murders or explosions” since the start of the year.

Twelve people died and five others were injured in attacks last month that Thornberg described as “terrorist-like violence.” The attacks are linked to criminal gangs that often recruit teenagers from socially disadvantaged immigrant neighborhoods to carry out hits.

Some 42 people have died in 290 shootings in Sweden this year, according to official police statistics. Authorities say the surge in violence is related to a feud between rival factions of criminal gangs led from abroad.

Sweden’s center-right government has said the country’s armed forces should work with police, but the military assists only with knowledge of explosives, helicopter logistics and analyses. The police and armed forces work out the details of such cooperation, which has not been made public. For the military to be involved in crime-fighting in any capacity is a highly unusual step for Sweden, underscoring the severity of the gang violence.

In the early hours of Tuesday, seven fires broke out in dwellings, each fueled by inflammable liquid, Thornberg said. Three people were later detained over the fires, he added, noting that most were “linked to an internal conflict.” Thornberg said most perpetrators “are prepared to commit serious acts of violence for a sum of money or other reward.”

More than 400 people have been detained this year for firearm-related crimes and about 100 others for crimes involving explosives, Thornberg said.

“The number of suspects under the age of 18 has increased by almost 30%,” he said. Swedish police say that criminals recruit people under 18 because they do not face the same police controls as adults and since juvenile perpetrators are often shielded from prosecution.

Hanna Paradis, a senior officer with the national police’s unit in charge of the recent events, said that ”despite the fact that we arrest more network criminals and seize more drugs, weapons and explosives, the development continues.”