The governor of Missouri stood down the police force that had been leading the policing of demonstrations against the killing of an unarmed 18-year-old, after Barack Obama added his voice to widespread criticism of a military-style crackdown.

Jay Nixon handed responsibility for law and order to the Missouri state highway patrol, led by an African American captain raised in the town at the heart of four nights of violent confrontation since the shooting of Michael Brown by police on Saturday.

On Thursday night the change appeared to be paying dividends — tensions were melting away and an almost festive atmosphere broke out, with police stopping to chat with demonstrators and residents.



“We all have been concerned about the vision that the world has seen,” Nixon said. He admitted that Ferguson, a suburb of St Louis had, come to resemble a “war zone”.

Promising a “softer front”, Nixon said that a new command would ensure that “we allow peaceful and appropriate protests, that we use force only when necessary, that we step back a little bit”.

But Nixon declined to rule out the use, if necessary, of the military equipment deployed so controversially on Ferguson’s streets this week.



Ronald Johnson, captain of the highway patrol, signalled a different tone. He told reporters: “Before I came here today, I had all my troopers take their teargas masks off their belts”. Johnson promised a new approach and said he would visit the torched QwikStop gas station “that has been called Ground Zero” to talk to people.

Nixon said that St Louis county police, although removed from the front line, would continue to lead the investigation into Brown’s death. He added that the name of the officer who shot the 18-year old dead, for which the campaigners filed a lawsuit on Thursday, should be released “expeditiously as possible”.

Speaking from Martha’s Vineyard, where he is on vacation, Obama said that while looting and violence against law enforcement officials was unacceptable, there was “no excuse” for police to use excessive force in response.

“We lost a young man in heartbreaking and tragic circumstances,” Obama said. “He was 18 years old and his family will never hold Michael in their arms again.”

Appealing for restraint, he added: “Now’s the time for healing, now’s the time for peace and calm on the streets of Ferguson.”



Obama’s comments came after a fourth night of confrontation in Ferguson, where residents of the majority black town of 21,000 people have been protesting against the killing of Brown by an officer from the overwhelmingly white police force.



The response to the protest had been led by the St Louis County police force, which has deployed snipers, armoured vehicles and officers in military combat gear to quell protests on successive evenings since Brown’s death on Saturday. Two reporters, with the Washington Post and the Huffington Post, were arrested on Wednesday night.

Obama condemned the arrest of reporters. “Here in the United States of America, police should not be bullying or arresting journalists who are just trying to do their jobs.”

Missouri governor Jay Nixon speaks about the unrest in Ferguson to residents and community leaders during a church forum. Photograph: Scott Olson/Getty Photograph: Scott Olson/Getty Images

The senior US senator for Missouri, Claire McCaskill, said she had been working to “demilitarise” the situation. She said on Thursday: “This kind of response by the police has become the problem instead of the solution. I obviously respect law enforcement’s work to provide public safety, but my constituents are allowed to have peaceful protests, and the police need to respect that right and protect that right. Today is going to be a new start, we can and need to do better.”

Heavily armed police officers from various forces fired gas canisters, rubber bullets and pepper balls at hundreds of young, predominantly African American protesters for several hours on Wednesday night after bottles were thrown at them from a largely peaceful protest.



The crowd had gathered in the centre of Ferguson, a suburb north of St Louis, to again demonstrate their fury at the shooting of Brown last Saturday. Police say that Brown was shot after assaulting the officer, but a friend who was walking with him, and witnesses to the shooting, say that he was shot repeatedly while attempting to run away from the struggle.



The officer, a member of the 53-strong Ferguson city force, has not been named and the police have declined to offer a detailed timeline of what happened. The lack of information being made public has seemed only to inflame the protests.

Several members of the crowds who fled Ferguson to escape the crackdown, a city with a population that is two-thirds black, told the Guardian on Wednesday night that they felt under fire from a militarised and almost unanimously white police force.

However, the city force was defended by mayor James Knowles, who said that they were “under a great deal of stress” and dealing with “a lot of unlawfulness”.

“I can’t second-guess these officers,” Knowles told MSNBC. “They are the professionals. They have learned from many years of dealing with these incidents across the nation. We’re just going to have to try our best to maintain order, and we ask the citizens to help us comply with that.”

Responding to criticism of the police tactics, Brian Schellman, a spokesman for St Louis County police, said on Thursday that commanders on the ground had authorised “whatever force was necessary for the situation”.

“Luckily for both sides, there’s been no lethal force used,” Schellman told the Guardian. “But what has been used is things like molotov cocktails. Those are deadly weapons. So the police response to the molotov cocktails was less lethal munitions. We’re not using deadly force when a deadly force molotov cocktail was used on us.”

Schellman could not confirm that any molotov cocktails or bottles had actually struck any officers. “But does that make it OK for people to throw? I don’t know,” he said. “To me it doesn’t. It doesn’t make it OK. To say ‘It doesn’t really matter because they didn’t hurt any of the officers’, we can’t think like that.



“So, do we have to wait until one of our officers gets hurt? That’s the big question here.” Asked if he meant that the answer was “No,” Schellman said: “Absolutely.”



Speaking late on Wednesday night at the police command centre, Schellman said officers had used “as much restraint as we could given the situation”, adding: “We have not had any violent uses of force ... no gunshots, no using batons in an aggressive manor, and no civilians injured.”

A police officer aims his weapon at a demonstrator in Ferguson, Missouri on Wednesday. Photograph: Mario Anzuoni/Reuters Photograph: MARIO ANZUONI/REUTERS

There was growing anger on Thursday at the arrest of two journalists, detained as they were working in a McDonald’s near the scene of the protests.

“That behavior was wholly unwarranted and an assault on the freedom of the press to cover the news,” said Washington Post executive editor Martin Baron about the arrest of reporter Wesley Lowery. “We are appalled by the conduct of police officers involved.”

The Huffington Post called the arrests, including that of its reporter Ryan Reilly, the result of police militarization that is “now beginning to affect press freedom”.



The reporters were seen being loaded into an unmarked police van. They were later released without charge, apparently after the intervention of the Ferguson police chief.

Separately, the Guardian witnessed teargas being shot directly at a camera crew with al-Jazeera America. Photographs later showed police officers dismantling al-Jazaeera’s broadcasting equipment after the crew fled.