PNG MORE
Business & finance
Glyph
24x24 Free Application Icons
stop, Abort, Block
Black
24x24
Attack, Error, Alert
DarkSlateGray
Error, sign, Blocked
Red
Alert
Salmon
PNG ICO ICNS MORE
Network & communications
Pixel
16x16 Free Application Icons
prohibition, danger, reject
Firebrick
16x16
Caution, warning, danger
danger, wind, Gesture
PNG ICO ICNS SVG MORE
Outline
iOS 7 icons
flag, Alert
512x512
Mixed
3D
Noiro
Alert, warning
Chocolate
128x128
Desktop apps
Handdrawn
Sketchy Icons v 1.2
Copy, red, Alert
256x256
Signs & symbols
Free 3d Glossy Interface Icon Set
Attention, Error, cautious
64x64
Hand, warning, Abort
warning, danger, Alert
Prompt, danger, exclamation
Message, help, Prompt
OrangeRed
Prompt, help, danger
E-commerce & business icons
UI
Mini icon set Part 1
48x48
Folder, Alert
Gray
Alert, Folder
DarkGray
Flat
Pretty Office 9
Alert, Email
Gold
Smooth
All Google icons
O, Alert
DarkOrange