Security was tightened at the White House in Washington following a shooting that left two National Guard soldiers critically injured.

Footage shows the tense lockdown as helicopters circled low over the Capitol area and streets around the White House were sealed off on Wednesday afternoon.

The attack reportedly happened around two blocks from the White House, where shots rang out as alleged gunman Rahmanullah Lakanwal, 29, opened fire on the officers.

Other troops rushed over and subdued him. He was taken into custody after being shot and hospitalised.

The suspect was an Afghan said to have entered the US in 2021, through a Biden administration program evacuating Afghan refugees to the country.

US President Donald Trump has described the 'heinous assault' as 'an act of evil, an act of hatred and an act of terror'.

He added: 'We must now re-examine every single alien who has entered our country from Afghanistan under Biden.'

Some 500 more National Guard members were deployed to Washington after the attack.

FBI director Kash Patel said the attack was being investigated and 'will be treated at the federal level as an assault on a federal officer'.