Christians from the World Victory Centre sing hymns during an Easter crusade service in Nairobi for the victims of the Garissa University attack. (Thomas Mukoya/Reuters)

Authorities have identified one of the al-Shabab gunmen responsible for the massacre last week at a Kenyan university that killed 148 students as the son of a Kenyan official.

A chief in Mandera County had reported his son missing last year, fearing that he had gone to Somalia to join al-Shabab. His worst fears were confirmed Sunday, when his son, Abdirahim Mohammed Abdullahi, was named as one of the gunmen in the attack at Garissa University College on Thursday. Security forces killed all the four attackers.

Abdullahi had graduated from the University of Nairobi with a law degree in 2013.

A Garissa-based official who did not want to be named told the news agency Reuters that Abdullahi had joined the Islamist militant group after graduating. “He was a very brilliant student. But then he got these crazy ideas,” the official said.

The governor of Mandera County, Ali Roba, acknowledged the increasing presence of al-Shabab in Kenya, telling Reuters that the nation had “massive radicalization problems, not only in the northern counties, but across the country.”

Relatives and colleagues of those killed in the deadly attack at Garissa University in Kenya faced the grim task of idenitifying them. Al-Shabab militants stormed the school last week, killing 148 people. (Reuters)

The news about Abdullahi came as Garissa’s Christian residents celebrated Easter Sunday. Garissa’s minority Christian population has been on edge since the news broke that Christian students were the primary target of the Thursday attack. Tensions ran particularly high as Easter Sunday services opened throughout predominantly Christian Kenya.

And yet, the pews of the Catholic church in Garissa were full, packed with residents coming to worship and mourn in the aftermath of Kenya’s worst terrorist attack in almost two decades.

“We encouraged the Christians first of all to take what has happened in a positive way, not to have that anger to revenge,” said the Rev. Clement Khiyaniri, preaching reconciliation. “They should not take it as a religious issue because it’s not Christians versus Muslims. These are terrorists who are killing people even in their own land.”

Security was ratcheted up at churches throughout Kenya, amid fears that al-Shabab was planning more attacks.

“Kenyan cities will run red with blood,” the group threatened after the Thursday attack, according to the SITE intelligence monitoring group. “No amount of precaution or safety measures will be able to guarantee your safety, thwart another attack or prevent another bloodbath.”

The service at one church in Mombasa, a coastal city with a predominantly Muslim population, was abruptly interrupted when security concerns forced an evacuation, Reuters reported. A bomb disposal unit was then deployed to investigate a suspicious vehicle parked outside the church.

The news agency said that in Nairobi, police officers wielding AK-47s guarded Holy Family Basilica cathedral, and plainclothes officers were reported to be inside.

Life in Garissa is slowly gaining a degree of normalcy. A day after 2,000 residents turned out to view the bodies of the four suspected gunmen displayed at Garissa Primary School, a children’s soccer game was going on in the school playground. Staff at the Garissa hospital were relieved to see most of the patient beds empty.

“There was an influx of a huge number of casualties, there was an overwhelming number of bodies, and the staff on the ground worked tirelessly day and night. Hopefully, we don’t get that kind of a situation again,” Bashir Abdi Aden, a doctor, said.

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