Nikhom Thephakaysone has been charged with murder (Picture: SPD/AP)

Passengers were too engrossed in their phones and tablets to notice a gunman brandish his firearm several times before shooting a student in the head.

CCTV footage from the carriage shows the gunman waving a .45 calibre pistol around before settling on a random victim.

Justin Valdez, 20, died after being shot in the back of the head in the attack, which took place in San Francisco in the US last month.

‘These weren’t concealed movements. The gun is very clear,’ said district attorney George Gascon.


‘These people are in very close proximity with him, and nobody sees this. They’re just so engrossed, texting and reading and whatnot.’



He added: ‘They’re completely oblivious of their surroundings.’

The memorial page for Justin Valdez

Nikhom Thephakaysone, 30, was later arrested and has pleaded not guilty to Mr Valdez’s murder and other charges.

Police said that rail travellers were often so absorbed by their mobile devices they left themselves open to crime.

‘Oftentimes when you interview people who get their phones stolen, when you ask them to describe where the person came from, what he was wearing, they have no idea,’ said police chief Greg Suhr.

Meanwhile, a message on a memorial page to Mr Valdez said: ‘Even though we regard his passing with the utmost sorrow, more importantly we must honour his memory and celebrate his life.

‘We must grieve so that we can come to terms with what has been lost, and what will be different. But we must continue onward, taking with us the great and the good that can be found. Justin is one such man from whose life there is so much great and so much good.’