President Donald Trump has called for vigilance and what he termed “extra level of safety” following the multiple terrorist attacks in London on Saturday night in which death toll has risen to nine.

Trump was briefed of the incident by the National Security Adviser, Herbert McMaster, according to the White House Press Secretary Sean Spicer.

The terror incidents reportedly left unconfirmed number of people dead and injured after van ploughs into pedestrians on London Bridge and Borough Market.

A third incident at Vauxhall, was, however said to be an isolated attack unconnected with the two other terror attacks.

Trump tweeted shortly after the attacks: “We need to be smart, vigilant and tough.

“We need the courts to give us back our rights.

“We need the Travel Ban as an extra level of safety!

“Whatever the United States can do to help out in London and the U. K., we will be there – WE ARE WITH YOU. GOD BLESS!”

The New York Police Department (NYPD) Counter-terrorism bureau said it was “deploying officers to heavily-travelled pedestrian locations across the city”.

NYPD spokesman Peter Donald said: “We’re monitoring the situation in London and we’re in touch with British authorities”.

NYPD said on its Twitter handle on that: “There are no specific, credible threats to NYC.

“Go about your Sat. night, NYPD cops are protecting you. Our prayers are with all in London”.

The U.S. Department of State also said: “We stand ready to provide all possible consular assistance should we become aware of any affected U.S. citizen.

“We strongly encourage U.S. citizens in the United Kingdom to directly contact concerned family members in the United States to advise them of  your safety”.

British Prime Minister Theresa May had earlier confirmed the attack as potential acts of terrorism.

“Following updates from police and security officials, I can confirm that the terrible incident in London is being treated as a potential act of terrorism.

“This is a fast moving investigation. I want to express my huge gratitude to the police and emergency services who are on the scene.

“Our thoughts are with all those who are caught up in this tragic event”.

Meanwhile, Facebook  has activated its “Safety Check” feature  after reports of the attack. The tool has been used in the past to inform friends and family about the welfare of individuals near a crisis.

Metro UK reported that the tool has been used in the past during the Orlando attack and the attack at the Westminster Bridge.

The Telegraph reported that it is the third time that the feature has been activated in the United Kingdom.

The page is called, “The Attack in London, United Kingdom,” and individuals can check in as safe.

Facebook first introduced the feature in 2011, and it was mainly used during natural disasters, like earthquakes. In 2015, it was used during the Paris attacks.

Fox Business reported that the safety check has been activated more than 600 times in two years and was last used in the UK last March during the Westminster attack in London.

According to Facebook, it is enacted after global crisis reporting agencies NC4 and iJET International alert the company about an incident.

Facebook then begins to monitor for posts about the incident, in the area, and if a lot of people are talking about it, they may be prompted to check in and mark themselves safe and invite others to do the same.