Officials in Arizona are on high alert after a shooter killed 11 people and wounded at least four police officers in a shooting Saturday morning at a synagogue in Pittsburgh.

Over the weekend, Valley-area police departments have stepped up visibility around houses of worship. Patrols in Chandler, Mesa, Tempe and Scottsdale were increased, with special attention for synagogues.

Although there have been no credible threats to religious institutions in the Valley, police are asking worshipers to be aware of their surroundings.