[bugs_bunny]

It wouldn't be quick, and it would be ugly, as explained in...

https://news.nationalgeographic.com/news/2009/04/090403-gamm...

and

https://astrobiology.nasa.gov/news/how-deadly-would-a-nearby...

BUT, such events are (apparently) every billion years or so...

[danielbarla]

I think that on average, there's a GRB close enough to us to matter once every billion years or so. However, it'd still need to be aligned perfectly to hit us, making the actual extinction event far less likely.