Gunmen killed themselves following mosque shooting which left three dead in San Diego

Police tape is placed near the scene of a shooting outside the Islamic Centre of San Diego (Gregory Bull/AP)

Two teenagers opened fire at a San Diego mosque on Monday and killed three men before killing themselves a few blocks away, police said.

The attack at the Islamic Centre of San Diego is being investigated as a hate crime, San Diego Police chief Scott Wahl said at a news conference at a neighbourhood park across from the mosque.