In Donald Trump's America, a president uses tear gas to get a photo opportunity

It was around 6.35pm that the tear gas was fired. Hundreds of protesters had gathered by the park just north of the White House under the clear blue sky.

Moments earlier some in the crowds had been urging the policemen in riot helmets and shields to “take a knee”, a sign of support for their cause, and chanting “no justice, no peace”.

Then, suddenly, the officers push forward. Huge bangs startled the crowds and sent many sprinting away from the front line. Plumes of tear gas forced others back.

The officers by foot strode forward while around a dozen followed on horseback. There were screams when each explosion rang out. Some chanted “hands up, don’t shoot”.

Around the time the action broke out Donald Trump was due to be addressing the nation from the other side of the White House, in the Rose Garden.

Yet there was confusion about why the police were acting now. There was still 25 minutes until the curfew officially came into force at 7pm.

Officers pushed the protest back a block before forming a new defensive line. There were more than 50 law enforcement standing in rows.

Some were park police holding black shields, others were mounted on horseback or holding truncheons. A handful wore camouflage and had “military police” written on their shields.

The reason for the timing only later became clear. Mr Trump, after declaring himself a “law and order” president, marched across the park - Lafayette Square - where the protest had been moments before. He did so for a photo call.

Mr Trump posed with a bible outside a church whose basement was set on fire on Sunday night, St John's Episcopal Church, in an apparent message of defiance to the protests that had forced him into a White House underground bunker on Friday night.

But that was not known to the hundreds of protesters who stood face-to-face with the officers just a minute or two’s walk away.

Many stayed in defiance as 7pm passed and the curfew kicked in.

Giovanny, a 28-year-old Washington DC resident, said he was startled when the tear gas and flash bangs went off.

“Oh man, as soon as I saw that the first thing I did was panic and run,” he told The Telegraph.

Asked why he was defying the curfew, he said: “I’m here for the support. I’m here for peaceful protest. I’m here for justice.”

Chris, 39, was also among those who stayed put despite the gathering becoming illegal.  “I’m native American. I’ve grown up with racism all my life,” he said, mouth covered with a bandanna.

“I’m just walking around. If people need help, I’ll give help.”

As it became clear the police would not advance further and tensions reduced, protesters gradually began to leave.

One man with a backpack called on fellow protesters to go home and come back tomorrow. Someone handed out pizza. By 8pm just a few dozen protesters remained at the spot.