Egypt has been rocked by the worst outbreak of violence since former President Mubarak was overthrown in February.
About 25 people were killed and hundreds wounded at a rally of Coptic Christians in Cairo.
They were demonstrating against a recent attack on Coptic churches in southern Egypt.
At least 40 people have been arrested and Egypt's ruling military is promising a speedy investigation of Sunday's violence.
The White House called for restraint Monday saying that the rights of religious minorities must be respected.
Anchor Marco Werman talks to Cairo-based reporter Noel King to get more details.