CAIRO (AP) -- A homemade bomb exploded near a traffic police post on a bridge over the Nile River in central Cairo early Tuesday, wounding two policemen and a civilian, security officials said.
Police sealed off the blast site on the al-Galaa bridge in the Dokki neighborhood, and a bomb disposal team combed the area to make sure there were no other explosive devices, the officials said on condition of anonymity because they were not authorized to brief the media.
Egypt's MENA state news agency said two policemen were wounded in the explosion, but made no mention of a civilian casualty. Such discrepancies are common in the aftermath of similar attacks.
There was no immediate claim of responsibility for the blast.
Islamic militants have carried out a series of bombings - with both crude devices and more sophisticated ones - in recent months targeting Egypt's security forces.
Militant groups that have claimed responsibility for some of the past attacks oppose the army's toppling last year of Islamist President Mohammed Morsi as well as the military-backed government that has taken his place.
Since Morsi's removal last July, the Egyptian capital has witnessed increasing violence and attacks - including a car bombing that struck Cairo's main security headquarters and a failed assassination attempt on the interior minister. There has been a lull, however, in high profile attacks, although small ones like Tuesday's appear to be growing more frequent.
Though small, the bombing on the traffic booth underlined the ability of suspected militants to carry out attacks in the heart of the heavily policed capital, a metropolis of some 18 million people.
In a separate development, a court in the coastal city of Alexandria ruled to bar members of Morsi's Muslim Brotherhood from running in parliamentary or presidential elections. The court ruling takes immediate effect unless appealed.
The military-backed government already has declared the Brotherhood a terrorist organization. Tuesday's ruling appeared to merely further reinforce the group's exclusion from public life.
The legal maneuvers have taken place amid a massive crackdown against Brotherhood members and the group's supporters. In the nine months since Morsi's ouster, Egypt's security forces have detained at least 16,000 Islamists and killed hundreds in clashes.
Morsi and most of the Brotherhood leadership are on trial over a wide range of charges that include espionage, conspiring with foreign powers and inciting murder. Some of the charges carry the death penalty. The Brotherhood says the trials are politically motivated.
Another Egyptian court on Monday convicted 24 students of belonging to a terrorist group - the Brotherhood - endangering public safety and assaulting police. The court, in Cairo's eastern Nasr City district, sentenced them to five years in prison and referred an underage defendant in the same case for trial in a juvenile court.
The court said the defendants were convicted for taking part in street protests last January that aimed to disrupt a two-day national referendum on a new constitution. The charter was authored by a mostly liberal 50-member panel picked by Interim President Adly Mansour. It replaced a constitution drafted in 2012 by Islamists.