September has become the worst month for shooting deaths in Sweden since records began in 2016, after two people died in separate shootings on Wednesday night, bringing the monthly total to 11.

Another person died on Thursday morning after a bomb blast.

The country has been rocked by a deadly wave of shootings and explosions in recent weeks – many suspected to be linked to a split within the Foxtrot criminal gang.

In the first of the shootings on Wednesday, an 18-year-old man was killed in the early evening at a busy sports ground in the south-west Stockholm suburb of Mälarhöjden, where children and young people were training.

At about midnight a second man was shot dead in Jordbro, just south of Stockholm.

A 25-year-old woman then died in hospital from injuries sustained when a bomb went off in Storvreta, outside Uppsala, a university city north of the capital, on Thursday.

The blast, which damaged five houses, is being treated by the police as a murder. Swedish media said the woman who died was probably not the target.

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Three people have been detained on suspicion of complicity in the Jordbro shooting, and two have been arrested over the Uppsala explosion, which was so violent that the facades of two houses were blown away.

In response to the latest incidents, Sweden’s national police commissioner, Anders Thornberg, said: “Innocent people are being murdered and injured.”

The police were doing everything in their power to stop the violence, he added. “Criminal conflicts in Sweden are a serious threat to the safety and security of the country.”

In a national address on Thursday night, the prime minister, Ulf Kristersson, said it was “a difficult time for Sweden”, blaming “political naivety” and “unsuccessful integration”.

Kristersson, whose minority-run government came into power a year ago after an election dominated by debates on gang crime, added: “Sweden has never seen anything like it. No country in Europe has seen anything like it.”

Pledging to “chase” and “defeat” the gangs, he said those involved would be sent to court and that if they were from outside Sweden, they would be deported.

Swedish law, he said, was not built for “gang crime and child soldiers” and that they would put in place all the resources needed. “Everything is on the table,” he said.

Kristersson said he would meet Friday with the national chief of police and the commander in chief of the military “to see how the armed forces can help the police fight the gangs.”

For several years Sweden has been in the grip of a conflict between gangs fighting over arms and drug trafficking, involving firearms and bombs.

Magdalena Andersson, a former prime minister and the leader of the main opposition Social Democrats party, called for the military to be drafted in to help with policing duties such as protecting government buildings so police could focus on stopping and investigating violent crime.

In a press conference in Stockholm, Johan Rydwik, the head of the capital’s regional investigation unit, said multiple preliminary investigations were under way. While the crisis mainly concerns Stockholm, he said, the rest of the country was also being affected.

“This problem cannot be approached based on geographical boundaries,” he said. “Our ability to share information and put puzzles together is vital.”

A police spokesperson said officers were frantically working to investigate and stop new acts of violence.

“It’s not a fun morning to wake up to,” Magnus Jansson Klarin told the broadcaster SVT. “From the police’s side, it is important to continue and do everything we can to prevent events like this with very disastrous consequences.”

Much of the violence is thought to be directed at relatives of people in criminal networks, and Jansson Klarin said keeping track of everyone was impossible.

“There are a lot of relatives,” he said. “We know that some people have left and gone to safety at new addresses … It is a very strained situation.”

Sweden’s centre-right government has been tightening laws to tackle gang-related crime, which Thornberg has previously described as bringing an “unprecedented” wave of violence to the country.

In 2022, there were 391 shootings in Sweden, 62 of which were fatal, while 45 people were killed by gunfire the previous year.