An aerial view of the area surrounding the Parsons Green Tube station in London, with the affected train in the distance. The affluent area is located in southwest London. (Photo: Screen grab from Sky News)

(CNSNews.com) - An improvised explosive device -- a crude bomb in a white bucket -- exploded on a London Tube train as it pulled into the Parsons Green station during the Friday morning rush hour, injuring 22 people, some of them in the stampede to escape the train car and others with burns, press reports said.

British Prime Minister Teresa May is calling it terrorism: "My thoughts are with those injured at Parsons Green and emergency services who are responding bravely to this terrorist incident,” she tweeted on Friday.

President Donald Trump also tweeted his disgust early Friday morning:

"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! 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!"

Trump also addressed his travel ban on people who cannot be vetted because they live in failed states: "The travel ban into the United States should be far larger, tougher and more specific-but stupidly, that would not be politically correct!"

And in a fourth tweet, the president addressed the general war on terror: "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!"

Sky News reported that the bucket bomb did not fully explode, so it appears the situation could have been worse. Sky News also reported that authorities are still looking for a suspect or suspects.