An Interior Ministry statement identified the man killed in the explosion near the Egyptian Museum as Ihab Yusri Yasin, and said he jumped from the bridge during a pursuit, setting off the explosive he was carrying.
Hours after Yasin was killed, two fully veiled young women opened fire on a tour bus on the Salah Salim highway, one of the main arteries through the south of the city.
A total of 10 people, including tourists, were injured in the attacks.
Security officials have told Aljazeera.net Yasin was one of the most wanted men in connection with the 7 April bombing near the Khan al-Khalili bazaar.
The two veiled women were identified by the Interior Ministry as the bomber's sister Negat Yousri and his fiancee Iman Ibrahim Khamees.
The ministry said that after the bus attack, Negat shot and wounded her companion and committed suicide. Khamees died in hospital of her wounds.
All three are reported to have been related to Ashraf Said, a suspect in the 7 April bombing who died in police custody a few days ago.
General Fuad Allam, former head of Egyptian security, believes the attacks were poorly coordinated and executed and not the work of a terror organisation.
"I believe that this is an individual act. What happened today is the aftermath of the al-Azhar bombing. The bomber in the Abd al-Munaim Riyad district was one of the most wanted men in connection with the al-Azhar bombing," he told Aljazeera.net.
Acts of revenge?
Muhammad Sayid Said, political expert at the Ahram Centre for Strategic and Political Studies, believes government torture of suspects might have been the motive for the revenge attacks.
"If the Interior Ministry's account is true, then these women were harmed some way or another very severely, and this bombing and shooting came as revenge. The family for sure suffered torture besides the disrespect that occurs in such circumstances [detention]," he told Aljazeera.net.
The issue of torture in Egypt's prisons was highlighted in a report by an Egyptian human rights group last month. The National Supreme Council for Human Rights (NSCHR) supported claims by international monitors that detainees were tortured during investigation, sometimes leading to their deaths.
The report also highlighted the death of a detained member of the outlawed but generally tolerated Muslim Brotherhood due to inadequate health care.
Fear of torture
Hisham Qasim, a leading member of the Kifaya (Enough) opposition movement, believes fear of detainment and torture might have pushed the relatives of Ashraf Said to acts of desperation.
The opposition say emergency
laws have fuelled violence
"If what was said about the bomber's act being a sort of revenge for his cousin who died in detention, then most probably those who were involved in this bombing and shootings were acting desperately to evade imprisonment.
"They know that if they got caught by security forces, they will be tortured to death. Killing themselves this way was their only way out to evade this," Qasim said, in reference to media reports that the two women fired on one another rather than risk being captured by police.
For its part, the Muslim Brotherhood condemned the attacks on Saturday and said: "We consider this to be in the benefit of the country's enemies. It contradicts the principles and teachings of Islam."
Isam al-Aryyan, a leading member of the brotherhood, said Saturday's attacks are a warning that Egyptian society has reached a boiling point.
"The involvement of two women is a very critical indicator, a phenomenon Egypt did not witness before. This means that people reached a state of irreversible despair that led them to the verge of explosion," he said.
Police sources said seven people,
including tourists, were injured
Al-Aryyan blamed the current lack of political reform in the country and the widescale detention of suspects without charge or trial.
"They [security apparatus] already have up to around 20,000 detainees in the prisons. All the political powers are circumscribed. The security forces have done everything that can be done.
"Security and political personnel have failed. They have to admit it and allow the people to elect a new president and have a new parliament. This is the only way out of this," al-Aryyan told Aljazeera.net.
Hasan Nafaa, head of the political science department at Cairo University, agrees. While he does not see the attacks on Saturday as part of a campaign to dislodge the government – such as in Saudi Arabia, for example - he stresses the need to look at dysfunction in Egyptian society.
"There is a large state of despair and loss of hope among the people. This kind of social problem may cause young teens to start doing stupid things such as suicide bombings," he said.
Nafaa believes Egypt's current emergency laws have neither stemmed acts of violence nor been conducive to the country's political environment.
"The emergency law should be removed to allow for some political liberation," he said.