A bomb blast aboard a train north of Cairo killed four people, including two policemen, and wounded nine, officials said Thursday, the latest attack by suspected Islamic militants battling the government of Egyptian President Abdel-Fattah el-Sissi.

The blast took place shortly before midnight Wednesday in the Nile Delta, the officials said Also late Wednesday, three people were wounded when a homemade bomb went off aboard a commuter train in the Cairo suburb of al-Marg, said the officials.

And on Thursday morning in Cairo, a woman was slightly wounded when a homemade explosive device went off near one of the city's presidential facilities, the infrequently used al-Quba palace, the officials said, speaking on condition of anonymity because they were not authorized to talk to media.

No one immediately claimed responsibility for planting any of the three bombs, but the attacks bore the hallmarks of Islamic militants fighting the government of el-Sissi, a general-turned-politician who took office in June, nearly a year after he led the military ouster of Islamist President Mohammed Morsi.

The attack on the Nile Delta train came hours after el-Sissi appointed two senior aides. Former Interior Minister Ahmed Gamal Eddin was named security adviser while career diplomat and former Cabinet minister Faiza Aboul Naga, who also served during the era of autocrat Hosni Mubarak, was named national security adviser.

Egypt has long battled Islamic militants in the Sinai Peninsula, but the unrest there escalated into a full-fledged insurgency since the ouster in July last year of former President Mohammed Morsi, an Islamist. The attacks, mainly targeting security forces, have spread to the Nile Delta and Cairo itself.

Attacks in Cairo have mainly involved small, homemade bombs that cause few casualties. But they have still revealed meticulous planning and execution by the militants and exposed inefficiency by the police. One such recent attack involved three homemade bombs that went off less than 20 yards from Cairo's presidential Ittihadiya palace, where el-Sissi conducts daily business. Two senior police officers were killed, one of whom was trying to defuse a bomb while in civilian clothes and without protective gear.

In the deadliest-ever militant attack on the military, at least 30 soldiers were killed late last month in Sinai, prompting el-Sissi to declare a state of emergency in northern Sinai and order the eviction of some 10,000 people from the town of Rafah on the border with the Gaza Strip.

El-Sissi's government has taken drastic measures to restore law and order and jumpstart the economy after three years of turmoil following the uprising that ended autocrat Hosni Mubarak's nearly three-decade rule in 2011.

But a recent series of deadly road accidents has underscored the persistently poor state of government services and infrastructure.

At least 18 people, mostly schoolchildren, died in a road accident north of Cairo on Wednesday, a tragedy that dominated the front page of every Cairo newspaper on Thursday. The accident prompted el-Sissi to order an overhaul of traffic regulations to stiffen penalties against offenders.

Last week, the burning death of a newborn baby in a private clinic caused a similar uproar. The baby was placed near a heater that caught fire. Graphic images published in newspapers of the baby's blackened body revived longstanding complaints about a culture of negligence and mismanagement.

Of the new el-Sissi appointments, Eddin served under Morsi but was fired after Morsi's Muslim Brotherhood accused him of failing to protect the presidential palace from protesters. He was close to el-Sissi, who was defense minister at the time.

Aboul Naga was at the center of one of the worst crises in Egypt-U.S. relations when, as minister of international cooperation in 2012, she led a campaign against nonprofit groups in Egypt, including key American organizations. She accused them of undermining the nation's security and using funds to spread chaos in the country. Sixteen Americans were charged with wrongdoing and tried in absentia after security forces raided their offices in December 2011.