Fake virus pop-up: what to do right now

Do not call the number

A pop-up that says your computer is infected and tells you to call a phone number is a scam. The FTC describes it as a fake warning that looks like it comes from a well-known company and urges you to call. Real security warnings do not ask you to call a number.

Do not call the number, and do not click inside the pop-up. A website cannot see inside your computer.

How to close it

Close the browser window or tab. On Windows press Ctrl+W, or Alt+F4 to close the window.
If it will not close, force the browser to quit. On Windows press Ctrl+Shift+Esc, pick the browser and choose End task. On a Mac press Command+Option+Esc, pick the browser and choose Force Quit.
If nothing works, restart the computer.
When you reopen the browser, do not restore the previous pages.

Afterward

Run a scan with security software you already trust.
Do not download anything the pop-up offered.
If you already called or let someone in, see what to do if you fell for a tech support scam.

Not sure if something is a scam?
Show it to Computer Support Inc. Snap a photo or type what you see and the AI tells you whether it is a scam. It is free, and nobody ever takes over your computer.
Is this a scam?

Sources

FTC: How to spot, avoid and report tech support scams

This guide is general information, not legal or professional advice. If money or personal information is at risk, contact your bank or card company right away.