DAISY ONYANGO, aged 20, hid from the gunmen for 12 hours as they went from dormitory to dormitory at Garissa University, in north-eastern Kenya, killing her fellow students by the score. From a window she could spot Kenyan soldiers. Why, she asked herself, were they not coming to save her?

As dusk fell that day, April 2nd, they finally stormed the residence. Within minutes, they had shot dead the students’ tormentors. Apparently only four-strong, they were members of the Shabab, a fanatical Islamist group that seeks to rule over Somalia and that has terrorised neighbouring Kenya because the government in Nairobi has been fighting it, in both Somalia and in Kenya. Garissa is a dusty little town in a poor ethnic-Somali area 145 kilometres (90 miles) from Kenya’s border with Somalia. Most of the students at the new university are, like Ms Onyango, from other parts of the country.

For the whole day, she and others had listened to the gunmen goading and giggling as they tortured and slaughtered her classmates, telling them that the Shabab’s mission was to “kill and be killed”. With time seemingly on their hands, they discussed where the Kenyan soldiers might be positioning themselves. Meanwhile, they tested the students’ knowledge of the Koran, killing those who failed. Some students had their throats slit. Others were shot. A few were reported to have been beheaded. Female students were tricked out of their hiding places by the gunmen’s assurance that the Koran forbids the killing of women. Some victims, before being killed, were made to call their parents to blame their death on Kenya’s government for policies that have supposedly led to the killing of Somalis and Muslims.

By the end of the day 142 students lay dead, along with six policemen and soldiers, plus the Shabab’s quartet. Apart from al-Qaeda’s bombing in 1998 of the American embassy in Nairobi, when 213 people were killed, it was the bloodiest atrocity in Kenya since independence in 1963. President Uhuru Kenyatta called for three days of mourning— and swore vengeance on the killers. He dispatched aircraft to bomb two Shabab camps across the border in Somalia. So far five Kenyan Somalis have been arrested on suspicion of involvement in the Garissa attack. Kenya’s central bank governor suspended the licences of 13 Somali remittance firms operating in Kenya and, according to Kenya’s Daily Nation newspaper, also froze the accounts of 86 individuals and entities “suspected to be financing terrorism in the country”.

Islamist assaults on Kenya have been mounting since 2011, when its government sent troops into Somalia to fight the Shabab, which proclaimed its allegiance to al-Qaeda in 2012 and still controls swathes of the country in the centre and south. Since then, the group has killed more than 400 people in Kenya. In September 2013 it butchered at least 67 in Nairobi’s upmarket Westgate shopping mall. In June last year it slaughtered 60 in the town of Mpeketoni, near the island of Lamu. In November and December it murdered 36 labourers in a quarry and 26 people whom it hauled off a bus. Both those atrocities were carried out near Mandera, in Kenya’s far north-east. In all such incidents, the Shabab released Muslims and killed the rest. Criticism of the government’s tardy and incompetent response to the slaughter in Garissa has welled up fast. A spokesman for the interior ministry insisted it was “not as bad” as during the Westgate fiasco, when security forces took four days to defeat four terrorists—and, by the by, looted the mall. Yet journalists were on the scene in Garissa hours before Kenya’s General Service Unit, a supposedly elite force which took seven hours to arrive from near Nairobi, 360km away, by road and aircraft. Police and soldiers based near Garissa itself were apparently unable to tackle the jihadists. Moreover, despite warnings that the university might be attacked, only two guards had been deployed to protect the students. The day before the attack, Mr Kenyatta had lambasted Western governments for warning their citizens against travel to certain parts of Kenya, specifically mentioning Garissa. After the Westgate attack he had been loth to sack any of the ministers or generals in charge of security, though eventually a few heads did roll. This time he will be expected to crack the whip a lot more fiercely.