People walk in front of Egyptian riot police are seen outside El Sadat metro station at Tahrir square in center of Cairo, Egypt May 13, 2018.
People travel on a metro train in center of Cairo, Egypt May 13, 2018.
An Egyptian riot police officer is seen outside El Sadat metro station at Tahrir square in the center of Cairo, Egypt May 13, 2018. REUTERS/Amr Abdallah Dalsh
People wait to board a train at El Sadat metro station in the center of Cairo, Egypt May 13, 2018.
People wait to board a train at El Sadat metro station in the center of Cairo, Egypt May 13, 2018.
People wait to board a train at El Sadat metro station in the center of Cairo, Egypt May 13, 2018.
People wait to board a train at El Sadat metro station in the center of Cairo, Egypt May 13, 2018.
People wait to board a train at El Sadat metro station in the center of Cairo, Egypt May 13, 2018.
Egypt beefs up security outside metro stations