President Donald Trump said Friday that Britain’s Scotland Yard was aware of the person who launched a terrorist attack on London’s subway during the morning rush hour.

The president tweeted that “a loser terrorist” committed the attack and said that person was “in the sights of Scotland Yard.”

London police were treating the blast at Parsons Green Tube station in West London as a terrorist attack.

London’s Metro newspaper reported that passengers suffered facial injuries from a blast and others were in a subsequent stampede. Police said 18 people were taken to a hospital for treatment of injuries that were not serious.