Why can't I find masks for the corona virus? Not an economist by far, just a layman, and that's a layman question.

How is this possible that it's difficult to find mask for the Corona Virus? I have been several times to 7/11, boots, Watson, and other pharmacies, and everytime they did not have it as they ran out. How is it possible that the producers of masks give up on additional earning by not producing more masks, now that it's pretty obvious the demand is going up?

The fact that there are not enough masks is my personal experience in Bangkok - however, some friends of mine have the same experience in Italy, where the Corona Virus outbreak has reached a scary stage.

Generally. I would explain capitalism failure by pointing at government regulations - however in this case I don't see how the government can be involved into mask production. 
Any idea?
The supply of masks can't keep up with soaring demand because mask producers have capacity constraints in the short run. See this recent article.