CAIRO (AP) - A massive pre-dawn car bomb by Islamic State extremists blasted the facade off a police headquarters Thursday and rattled windows across Cairo - wounding 29 but causing no deaths.
The attack reflected a strategy of the group's branch in Egypt, which has targeted authorities but avoided spectacularly bloody civilian casualties - at least for now.
Two years of violence in a militant campaign has left hundreds dead in Egypt, mainly police and soldiers, and a string of attacks in the capital have undermined President Abdel-Fattah el-Sissi's claim to bring order to the country.
The main, Sinai-based militant organization, which swore allegiance to the Islamic State group last year, has shown worrying signs of the Iraq- and Syria-based extremists' notorious brutality - most notably, the beheading this month of a Croatian captive.
But its strategy also shows differences with the Islamic State core, which has ruthlessly slaughtered civilians in Iraq, Syria and Yemen, including in suicide bombings in markets and mosques.
Thursday's attack in the Egyptian capital was the third time the group has carried out a large bombing at an hour when most people are asleep or off the streets - an apparent attempt to limit public outrage against the branch.
Its past similar attacks all led to few casualties or deaths, mostly among police. These include the dawn bombing of the Italian Embassy in Cairo last month, which killed one person; a huge truck bomb in January 2014 targeting Cairo's security headquarters, which killed four policemen; and a car bomb a month earlier that tore through a security headquarters in the Nile Delta city of Mansoura, killing 16 people, nearly all policemen.
The first two of those attacks were claimed by Ansar Beit al-Maqdis, as the affiliate was called when it began targeting the government following the military's ouster of an Islamist president in 2013 - and before it pledged allegiance to the IS group last year.
"The style of the attacks are a little different than what we've come to expect from the IS group, as there is an absence of mass casualties when it comes to urban areas," said H.A. Hellyer, a security expert at the Brookings Institute think tank in Washington. "That may be attributed to its recruitment strategies, but we can't assume that it won't change tactics going forward."
The differences are likely rooted in two factors. Egypt is overwhelmingly Sunni Muslim with a Christian minority of around 10 percent, and has virtually no population of Shiite Muslims, the community IS mainly targets in its worst mass attacks elsewhere.
Also, the Egyptian branch is a homegrown group whose original name, Ansar Beit al-Maqdis, means Champions of Jerusalem. It stepped up its insurgency in revenge for a police crackdown on Islamists following the military's 2013 ouster of Islamist President Mohammed Morsi. Its homegrown status likely makes it more attentive to local sentiment.
Thursday's blast, which went off just before 2 a.m., fits the group's pattern of attacks. It demolished a wall in front of the security building, bringing down watch towers and leaving gaping holes exposing its offices. Of those hurt, 11 were police and soldiers.
Authorities said high-powered explosives were used in the blast, which was heard and felt across the city, damaging nearby schools and court buildings. It also shattered colored glass windows and cracked the walls of a nearby palace built by Muhammad Ali, an early 19th-century ruler of Egypt.
Glass from blown-out windows littered the streets in the Shubra el-Kheima neighborhood, at the northern entrance to the capital. Security forces with assault rifles set up roadblocks to ward off onlookers and some hysterical residents. The blast left a 16-foot crater, and the engine of the pickup truck used in the attack landed more than a dozen yards down the street.