At least 44 people were killed and hundreds more were injured during protests demanding the reinstatement of ousted President Mohammed Morsi across Egypt on Sunday, NBC News reported. Another 283 were arrested. The clashes are a reminder that tensions remain deep three months after the army takeover of the Arab world's most populous country. Egyptian authorities had warned on Saturday that anyone who protested against the army during ceremonies marking an attack on Israeli forces during the 1973 war would be regarded as an agent of foreign powers, not an activist, according to Reuters. Meanwhile, in Cairo's Tahrir Square, thousands of supporters of the military waved Egyptian flags, blew whistles and touted posters of army chief Gen. Abdel-Fattah el-Sissi, according to the AP.