BERLIN  - German Chancellor Angela Merkel on Thursday rebuffed calls to reverse her welcoming stance toward refugees after a series of brutal attacks in the country.

Merkel, who interrupted her summer holiday to face the media in Berlin, said the four assaults within a week were “shocking, oppressive and depressing” but not a sign that authorities had lost control.

The German leader said the assailants “wanted to undermine our sense of community, our openness and our willingness to help people in need”. “We firmly reject this,” she said at a wide-ranging news conference.

Merkel repeated her rallying cry from last year when she opened the borders to people fleeing war and persecution, many from Syria, which brought nearly 1.1 million migrants and refugees to Germany in 2015.

“I am still convinced today that ‘we can do it’ - it is our historic duty and this is a historic challenge in times of globalisation,” she said. “We have already achieved very, very much in the last 11 months.”

Merkel was speaking after a axe rampage, a shooting spree, a knife attack and a suicide bombing stunned Germany, leaving 13 people dead, including three assailants, and dozens wounded.

Three of the four attackers were asylum seekers, and two of the assaults were claimed by the Islamic State group.

Merkel said that she would not allow militants, following a series of deadly attacks in France, Belgium, Turkey and the US state of Florida, to keep her government from being guided by reason and compassion. “Despite the great unease these events inspire, fear can’t be the guide for political decisions,” she said. “It is my deep conviction that we cannot let our way of life be destroyed.”

While the German political class has largely called for calm, opposition parties and rebels from Merkel’s own conservative bloc have accused her of exposing the country to unacceptable risks without stricter controls on people let in.

“Terrorism has unfortunately arrived in Bavaria,” the state’s interior minister Joachim Herrmann told reporters Thursday, renewing calls by his Christian Social Union party for an upper limit on the number of new asylum seekers. “We are awaiting urgent action from the federal government and Europe.”

Merkel announced a string of new security measures including improving an “early-warning system” to detect radicalisation among refugees, training the military to respond to major attacks, boosting intelligence cooperation with allies and speeding up deportation of rejected asylum seekers.

The deadliest attack came last Friday when a German-Iranian teenager who was born and raised in Munich opened fire at a downtown shopping mall, killing nine people before turning the gun on himself.

He had been under psychiatric treatment and investigators say he was obsessed with mass shootings, including Norwegian rightwing fanatic Anders Behring Breivik’s 2011 massacre.

They have ruled out an Islamist motive, saying the assailant had far-right “sympathies”. On July 18, an asylum seeker from Afghanistan or Pakistan slashed train passengers and a passer-by with an axe and a knife in Wuerzburg before being shot by police.

And on Sunday, a failed Syrian asylum seeker blew himself up outside a music festival in Ansbach, wounding 15 people at a nearby cafe after being turned away from the packed open-air venue. IS claimed both attacks.

Already steeped in grief and shock, Germans were further rattled by news that a Syrian refugee had killed a 45-year-old Polish woman with a large kebab knife at a snack bar in the southwestern city of Reutlingen Sunday in what authorities called a personal dispute.

The German attacks came with two state elections looming in September, in Berlin and in Merkel’s fiefdom of Mecklenburg-Western Pomerania.

The rightwing populist Alternative for Germany (AfD) party hopes to make a particularly strong showing there with a campaign against “Islamisation”, which would deal Merkel a stinging blow one year ahead of a general election.

Merkel’s popularity had suffered earlier this year, following a rash of sexual assaults in the western city of Cologne on New Year’s Eve blamed mainly on Arab and North African men. But her poll ratings had recently recovered as the refugee influx has slowed dramatically due to the closure of the Balkan migrant route and an EU deal with Turkey to stem the flow.

Analysts are awaiting new data to see what impact the recent attacks have had on her support.

German police have searched a mosque and eight apartments in Hildesheim that are believed to be a hotbed of a radical Salafist community, the interior minister of the northern state of Lower Saxony said on Thursday.

Germany is on high alert after a spate of attacks since July 18 left 15 people dead - including four attackers - and dozens injured. Two assailants, a Syrian asylum seeker and a refugee from either Pakistan or Afghanistan, had links to militancy, officials say.

Interior Minister Boris Pistorius said in a statement that up to 400 police - including mobile squads and a special forces police commando - were involved in the raids on Wednesday in the Hildesheim area, which is a short drive south of Hanover.

“The German-speaking Islamic circle (DIK) in Hildesheim is a nationwide hot-spot of the radical Salafist scene that Lower Saxony security authorities have been monitoring for a long time,” the state official said.

Pistorius said the search followed months of planning and was an important step towards banning the association, which security authorities say has radicalised Muslims and encouraged them to take part in jihad in combat zones.

Numerous members of the mosque have travelled to Syria and Iraq to join Islamic State, while sermons, seminars and speeches call for “hate against non-believers,” the ministry said.

Germany has seen sharp increases in the number of ultra-conservative Islamists known as Salafists in recent years, with the total number of sympathisers now seen at 8,900, up from 7,000 at the end of 2014, German officials have said.

Security authorities say the DIK in Hildesheim is believed to have become the focal point of Salafist activities in Lower Saxony, the second-largest of Germany’s 16 states after Bavaria.

“We will not put up with Salafist associations and their backers flouting our rules and bringing our rule of law into question and convincing young people that they want to join the so-called IS,” Pistorius said. “I’m convinced that our freedom is stronger than the inhuman ideology of the extremists,” he added. (