"I never think it's helpful for anyone to speculate," Prime Minister Theresa May said.
The president was quick to condemn the attack on a London subway train.
Passengers post images of a bucket as the suspected cause of the blast after a reported fireball in west London.
The founder of the Dutch team wants to start building a commercial hyperloop transport system between Amsterdam and Paris by 2021.
Engineering and psychology research can help improve evacuation procedures in subway attacks, like the recent St Petersburg bombing.
The terror threat level in the U.K. is set at 'severe,' meaning an attack is 'highly likely.'
Google's DeepMind creates AI that uses basic reasoning to find the quickest route on the Underground.
Kurdish activists blocked the entrance to Oxford Circus station in central London demanding greater support for forces fighting Islamic State