Blast heard outside Cairo court as referendum begins

Egyptian soldiers stand guard in the courtyard of a school that will be used as a polling station in Suez January 13, 2014. REUTERS/Al Youm Al Saabi Newspaper

CAIRO (Reuters) - An explosion was heard in Cairo just before Egyptians were due to begin voting in a constitutional referendum, the first ballot since the military ousted Islamist president Mohamed Mursi, security sources said on Tuesday.

The blast occurred near a court complex in the district of Imbaba. There were no immediate reports of casualties.