Cairo Metro
A protester opposing Egyptian President Mohamed Mursi waves the national flag as others stop a train at an underground Metro station at Tahrir Square in Cairo on Jan. 25, 2013. Reuters/Amr Abdallah Dalsh

Update as of 5:08 a.m. EDT: (Reuters) - Four small bomb blasts wounded at least five people in Cairo during the morning rush hour on Wednesday, security sources said, the first such casualties in the capital since Abdel Fattah al-Sisi became president this month.

(Reuters) - Two explosions wounded at least four people at two Cairo metro stations during the morning rush hour on Wednesday, security sources said, highlighting some of the challenges faced by newly elected President Abdel Fattah al-Sisi.

Explosions hit Ghamra metro station in central Cairo and Shubra El-Kheyma, a northern district of Greater Cairo, according to state television and security sources.

Three people were wounded at Shubra, according to security sources, and one person at Ghamra, according to the television report.

An interior ministry official told a privately owned television channel that one person was wounded carrying a home-made bomb to Shubra El-Kheyma station. He added the Ghamra incident was caused by an explosion in a rubbish bin.

Egypt has been hit by a wave of violence, mainly attacks by Islamist militants based in the Sinai Peninsula on security forces, since the army ousted Islamist President Mohamed Mursi in July following mass protests against him. Former army chief Sisi, who deposed Mursi, was sworn in as president after winning elections last month.

His supporters see him as a strongman who can save Egypt from chaos after more than three years of political and economic turmoil, following a 2011 revolt that swept veteran autocrat Hosni Mubarak from power.