Google's headquarters in Mountain View, California, received a threat on 8 April (Friday), following which a few buildings on the expansive tech campus were evacuated by local police. The Mountain View Police assisted Google security in responding to the threatening call.

The Mountain View Police Department later tweeted that a search of Google's HQ resulted in nothing suspicious being found and that no injuries to any Google employees were reported. No word on the details of the threat has been released, from either Google or the local police.

This is not the first time for a Silicon Valley-based tech firm has received a threat. In January, Apple's Ireland headquarters evacuated 4,000 employees after receiving a bomb threat. No employees were harmed and the local police's search found nothing suspicious.

In the face of rising extremist propaganda found online, many tech firms have pledged allegiance to combating terrorism on the digital front. As a result, tech titans have become the latest targets for extremist groups. Facebook CEO Mark Zuckerberg and Twitter CEO Jack Dorsey have both been threatened by Islamic State (Isis) for having shut down numerous IS-related accounts.

Since extremist groups like IS rely heavily on technology and social media to expand recruitment, the tech community's move to inhibit their online activities serves as a major source of frustration. Google recently proposed banning extremist groups like IS to the dark web, in order to ensure that their digital activities remain inaccessible to young and vulnerable netizens. The tech community's mounted defence has already considerably weakened extremist groups' online visibility in recent times.