Donald Trump Jr. on Wednesday mocked London Mayor Sadiq Khan for declaring last year that terrorist attacks are "part and parcel" of living in a big city, on the same day an apparent terrorist killed three people in London.

"You have to be kidding me?! Terror attacks are part of living in the big city, says London Mayor Sadiq Khan," Trump Jr. said in his tweet.

You have to be kidding me?!: Terror attacks are part of living in big city, says London Mayor Sadiq Khan https://t.co/uSm2pwRTjO — Donald Trump Jr. (@DonaldJTrumpJr) March 22, 2017



The tweet linked to an Independent article from September in which Khan said terrorist attacks are to be expected, and encouraged citizens of the city to be vigilant.

British police said four people are dead in London from Wednesday's attack, including one police officer and the attacker. They also reported at least 20 injured.