ON A sodden evening in Dadar, a middle-class neighbourhood in central Mumbai, one end of a bus stop still displays an ad for pro-biotic yoghurt. The other end is blown to bits. A tarpaulin, gathering water, has been hastily laid to cover the pavement next to it and a crowd is gathered nearby, including a man offering to trade gruesome photos taken on his phone. A local man says he heard the explosion and came out to see bodies being dragged away.

The bomb, like blasts in two other neighbourhoods in the south of the city, went off at about 7pm, during rush hour. Across Mumbai on July 13th bombs killed 18 people and injured 113, according to the chief minister of Maharashtra state.

The attacks were of middling complexity. The three near-simultaneous explosions in separate parts of the city would have taken some planning. And the crude devices inflicted a serious toll. But at least the most intense terror was fleeting.

By grim contrast, three years ago, a sophisticated and suicidal assault by ten well-trained gunmen on various sites, including a hotel, train station, Jewish centre and restaurant in Mumbai, was prolonged and intensely distressing. Some 170 people died over four days as hostages were shot and the Taj Mahal hotel burned, while officials flapped in response.

This time the authorities appeared much better organised, despite crowds and monsoon rain. Commandos, bomb experts, forensic and terrorist units were deployed promptly, some from Delhi. Politicians spoke to the public immediately and the home minister, Palaniappan Chidambaram, rushed to the scene. Public figures lined up to call for calm—in effect warning angry Hindus from rampaging against Muslims.

No group has claimed responsibility for the attacks. Fingers could be pointed at jihadis based over the border, notably Lashkar-e-Toiba (LeT), who were behind previous (and more audacious) strikes. Pakistani militants had earlier vowed revenge on America and its allies for the killing of Osama bin Laden. The attacks also come amid cautious but steady efforts by India's prime minister, Manmohan Singh, to restart peace talks with Pakistan, which collapsed following the 2008 assault. The countries' foreign ministers are to meet in Delhi this month. That should yet happen, especially since Pakistan's civilian leaders promptly condemned the latest attacks.

In any case, it is more likely that a homegrown Islamist outfit was to blame. Anti-terror police said they had arrested two men with weapons in a suburb of Mumbai on July 6th. They were allegedly part of Indian Mujahideen (IM), an Islamist extremist group which has claimed eight terrorist attacks, including similar bomb blasts in cities, in the past four years. The worst of these, a series of 21 explosions in Ahmedabad, Gujarat, on July 26th 2008, killed 56 people.

A member of the IM also claimed responsibility for the relatively sophisticated bombing that tore through Mumbai's suburban railway system in 2006, striking seven targets within an 11-minute span and killing more than 200 people. That attack was initially blamed on the LeT, but it might be significant that today's happened only two days after the fifth anniversary of those bombings. Given the IM's known methods—using hidden bombs in crowded streets—and a smaller but similar attack by the group in Varanasi in December, they are now seen as the most probable culprit.

That is worrying. Indian intelligence fears that young Muslims in the country are growing more radical. Some may be set on revenge for the pogroms in Gujarat in 2002, in which some 2,000 Muslims died at the hands of Hindu-nationalist mobs, while others are furious over the treatment of Muslims in Kashmir. And there are those who are converted to radicalism while working as migrant labourers in the Gulf. Some suspect that IM, despite its name, might also have links to Pakistani jihadists such as LeT. Whether these terrorists have connections abroad or not, there can be no doubt that India has become the unfortunate site of a kind of front-line.