The shooting at YouTube’s headquarters in San Bruno today brought a moment of unity to Silicon Valley, following a week of discord in which two of the most prominent technology leaders publicly sniped at each other.

A woman opened fire with a handgun in an outdoor courtyard Tuesday afternoon, injuring three people and sending scores of employees feeling in fear before apparently turning the gun on herself, according to police. As reports of an active shooter at YouTube headquarters spread via social media, industry leaders including Apple CEO Tim Cook, Amazon’s Jeff Bezos and Microsoft’s Satya Nadella turned to Twitter to express their condolences. Here is a sampling:

Uber CEO Dara Khosrowshahi extended his for YouTube and gratitude to first responders.

While Twitter CEO Jack Dorsey used the tragedy to renew calls for gun control, posting links to the March for Our Lives movement.

Google CEO Sundar Pichai acknowledged the support during the tragedy, while YouTube co-founder Chad Hurley Tweeted a brief note in the middle of the ordeal, expressing anxiety: “Praying for my friends @YouTube!”

Silicon Valley has been showing its sharp elbows in the past week, as Cook and Facebook Chief Executive Mark Zuckerberg have thrown rhetorical jabs at each other in interviews about the Cambridge Analytica data leak. Apple’s CEO said he “wouldn’t be in this situation”  because of Apple’s firm privacy stance, while Zuckerberg called those criticisms “extremely glib.”