[6] Al-Shabaab, a multi-ethnic militant group based in Somalia with links to Al-Qaeda, had killed over 200 people in Kenya in the two years prior to the event, in attacks like the 2013 Westgate shopping mall shooting.

[6] Diplomats and analysts had also criticized the Kenyan security forces' policing strategy, which they described as heavy-handed and which involved indiscriminate mass arrests of resident Somalis.

They further warned that such sweeping tactics would only result in creating resentment among Muslims, thereby providing Al-Shabaab with an opportunity to capitalize on the situation.

[4] The attack came a day after the Kenyan President Uhuru Kenyatta had chastised the United Kingdom and Australia for renewing their travel warnings over security threats in Kenya,[7] and accused them of perpetuating colonialism.

[10] 20 students were rescued by soldiers, including Collins Wetangula, who described the presence of at least five masked, armed gunmen, as well as Christians being "shot on the spot".

[13] They surrounded and sealed off the university to flush out the gunmen, with the Interior Ministry and Kenya National Disaster Operation Centre reporting that three out of four dormitories had been evacuated.

[14] A spokesman for the group, Sheikh Ali Mohamud Rage, said regarding the situation that "when our men arrived, they released the Muslims", but were holding Christians hostage.

The militant group indicated that the Garissa shooters wanted to "avenge the deaths of thousands of Muslims killed at the hands of the Kenyan security forces."

[7] Kenyan police were also searching for a close associate of Abdullahi's, who had received training with him in Somalia and later left for Yemen to reach Syria.

[23] On 15 November 2021, Ali Abikar escaped from prison with two other detained Al-Shabaab members,[24] but were later apprehended in Kitui County in South Eastern Kenya as they attempted to cross to Somalia, three days later by Kenyan authorities following a tip-off from locals of the area.

President Barack Obama, who visited Kenya in July 2015, expressed horror and sadness at the reports that students were killed in the attack.

[31] A Kenyan social media campaign on Twitter encouraged the use of the hashtag #147notjustanumber to humanize the victims, along with photos and names of those who had died in the attack.

[32] Nightly curfews from 18:30 to 6:30 were imposed until 16 April in Garissa and three other counties (Wajir, Mandera and Tana River) near the North Eastern Province's border with Somalia.

[34] The Kenyan authorities published a gazette notice listing Al-Shabaab and the Mombasa Republican Council separatist group as two of several terrorist organizations with operations in Kenya.

[34] The Kenyan government also called for the closure of the nearby Dadaab refugee camps, for fear that Al-Shabaab was using it as recruiting grounds for new members.

Wetangula also recommended that the Kenyan government cut its military budget in half, and reallocate the slashed funds toward strengthening internal security.

Additionally, Odinga accused Kenyan President Uhuru Kenyatta of conceitedness for having dismissed intelligence alerts of potential attacks issued by foreign nations.

[8] Ten days after the shootings, an explosion of a power transformer outside the student hostel at the University of Nairobi Kikuyu Campus sent pupils panicking in fear of another attack.

[38] Over the following weeks, 96 of the 150 primary and secondary schools in Garissa County closed over security fears, as many teachers have refused to return to work.