President Trump began tweeting early Friday morning about the explosion on a London tube train in London when only few details were known.

Mr. Trump blamed the attack on a "loser terrorist."

Another attack in London by a loser terrorist.These are sick and demented people who were in the sights of Scotland Yard. Must be proactive! — Donald J. Trump (@realDonaldTrump) September 15, 2017

Loser terrorists must be dealt with in a much tougher manner.The internet is their main recruitment tool which we must cut off & use better! — Donald J. Trump (@realDonaldTrump) September 15, 2017

The explosion at the Parson's Green London Underground train station left at least 22 people injured in a bombing attack, but no one died.

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The president then said that the travel ban introduced by his administration should be "far larger, tougher and more specific," though he did not know who might be behind the attack.

The travel ban into the United States should be far larger, tougher and more specific-but stupidly, that would not be politically correct! — Donald J. Trump (@realDonaldTrump) September 15, 2017

We have made more progress in the last nine months against ISIS than the Obama Administration has made in 8 years.Must be proactive & nasty! — Donald J. Trump (@realDonaldTrump) September 15, 2017

British Prime Minister Theresa May, when asked about Mr. Trump's comments on the situation, criticized his remarks.

"I never think it's helpful for anybody to speculate on what is an ongoing investigation," she said, adding that the police and security services are working to discover the full circumstances of the attack and to identify who are responsible.