Tonight the extraordinary moment on Capitol Hill met a CEO Mark Zuckerberg apologizing

to families after being told he has blood on his hands.

Zuckerberg testifying alongside several other tech CEOs standing and turning to the Dr. they say were harmed by social media. One mother who lost her son speaking to us,

but will social platforms get any safer?

Also tonight the US preparing to strike back

at Iran-linked targets and retaliation for the drone strike that

killed three soldiers. Why the response could last for weeks and who the U.S. now

says was responsible. The FBI director warning Chinese hackers are preparing to wreak

havoc on the US, the major targets they could strike. A shocking crime a man

arrested for allegedly killing his father then posting a gruesome

YouTube video dramatic body cam shown in court the moment police arrested the

parents of a Michigan school shooter. The major storm fueled by an atmospheric

river slamming the West Coast, when the worst will storm ashore. The pipeline

inferno flames shoot 500 feet into the year.

This is NBC Nightly News with Lester Holt.

Good evening everyone and welcome.

Today a reckoning for social media in this country over harm suffered by

some of the youngest and most vulnerable users children and why proposed

online safety measures have stalled. The CEOs of five popular social media

platforms appearing before the Senate Judiciary Committee today where they

faced angry lawmakers. We're told they have blood on their hands and were met by a gallery that included

child safety advocates and distraught parents. Many carrying large photos of

...