Kenya (CNN) Christians have come under repeated attacks in North Eastern Province in Kenya at the hands of Al-Shabaab militants who have killed hundreds.

It's sunrise over the Tana River. Traffic starts to flow over the bridge and morning rush hour begins. What looks like the beginning of a normal workday here has a much darker undertone. Most of the commuters are day laborers, people going into their offices, but also many Christians who are too scared to sleep inside Garissa town. They have decided to move themselves and their families across to the other side of the river to safety.

We met Esther as she was crossing the bridge on foot on her way to work. She is a mother of three and a Christian. When we ask her why she decided to move her and her family out of town she tells us: "It is because of Al-Shabaab that I moved out of Garissa. You can be shot anytime while you are walking. Even when we're at home they can just come from the bush."

In April this year, hundreds of students at Garissa University in northern Kenya came under attack when Al-Shabaab militants from across the border in Somalia raided dormitories at the college. Separating Christian students from their Muslim classmates, the raiders killed 147 and wounded dozens more . Today, the university stands empty.

Christians in North Eastern Kenya have come under repeated attacks by Al-Shabaab militants

At Sunday Mass in Garissa's Cathedral, Our Lady of Consolation, the benches are full. The congregation is praying under armed guard but they're praying nonetheless.

Photos: Leaders of deadliest terrorist groups Photos: Leaders of deadliest terrorist groups Mawlawi Haibatullah Akhunzada, named the new Afghan Taliban leader following the death of Mullah Akhtar Mohammad Mansour, is in his late 50s and comes from Panjwai district of southern Kandahar province. Hide Caption 1 of 7 Photos: Leaders of deadliest terrorist groups Ayman Al-Zawahiri is the leader of al Qaeda. He previously acted as Osama bin Laden's personal physician and is believed to have played an important role in the September 11 terror attacks. Hide Caption 2 of 7 Photos: Leaders of deadliest terrorist groups Abu Bakr al-Baghdadi is the leader of ISIS, the militant group that wants to create an Islamic state across areas of Iraq and Syria. Not much is known about the ruthless leader. A reward of up to $10 million has been offered by the U.S. government. Hide Caption 3 of 7 Photos: Leaders of deadliest terrorist groups Qasm al-Rimi is the leader of al Qaeda in the Arabian Peninsula. He succeeded Nasir al-Wuhayshi, who was killed in a drone strike . Al-Rimi has spent more than a decade at the helm of the military side of AQAP, and he also plans their large international operations. Hide Caption 4 of 7 Photos: Leaders of deadliest terrorist groups Mullah Fazlullah is the leader of the Pakistani Taliban. The group, which has links to the Afghan Taliban and al Qaeda, has claimed responsibility for shooting teen activist Malala Yousafzai and attempting to detonate a car bomb in New York's Times Square in 2010. Hide Caption 5 of 7 Photos: Leaders of deadliest terrorist groups Ahmed Omar Abu Ubaidah is the leader of al-Shabaab, an al Qaeda-linked militant group based in Somalia. Little is known about the man characterized as a low-ranking commander. Hide Caption 6 of 7 Photos: Leaders of deadliest terrorist groups Abubakar Shekau is the leader of Boko Haram, a militant Islamic group working out of Nigeria. Little is known about the religious scholar. He operates in the shadows, leaving his underlings to orchestrate his mandates. A reward of up to $7 million has been offered by the U.S. government. Hide Caption 7 of 7

Each Sunday brings with it new threats from Al-Shabaab. Garissa's Christians are told that if you worship here, you'll die. One of those attending Sunday Mass, Patrick Gitau tell us that despite the risks: "Every Sunday I'm here it's my cathedral. Yeah I'm here I was baptized in this church."

Leading this congregation in these uncertain times is Maltese priest Joseph Alessandro, now the Bishop of Garissa, who came to Kenya in the early 1990s.

He was shot by separatist militants on the Kenyan coast in 1993, and left the country to receive medical attention, but he was determined to return. He eventually came back to Garissa five years ago.

In spite of the threats that arrive before every Sunday mass, he says he would never consider leaving his congregation.

"It's not a matter of choice," he says. "It's our duty to remain here. Since we are appointed as bishops, we have to stay -- not withstanding what happens -- 'til there are no Catholics, it's our duty to stay."

In the wake of the attack, he says, many students stopped attending their classes.

"Before the Garissa attack, we had 460 students in our school. After the attack, only 300 reported back. The others left Garissa or were scared to come back [to school] because of the attack."

Alessandro says he hopes that the institutions forced to shut down because of the threat of terror will soon reopen and that life will return to normal.

"Now we are gaining confidence again -- we have security on the compound for the school and even during the night for the sisters, for the priests."

He along with his fellow bishops and nuns, have been a constant in this community.

Sister Evelyn Ingoshe, has been part of the Diocese of Garissa for two years. She works at the school next to the Garissa Cathedral. Sister Evelyn tells us that she loves children and it is for that reason that she has devoted her whole life to serve them.

Being fully aware of the risks involved she decided nevertheless to come and work in this part of Kenya where Christians have suffered many attacks and there are weekly, if not daily threats.

"I knew that there was a danger in coming to this place of the country for a non Muslim but I followed my heart and wanted to do it."

Photos: Kenyan schools live in fear of Al-Shabaab Photos: Kenyan schools live in fear of Al-Shabaab A young girl studies for class at the Ibnu-Siina school in Garissa, Kenya. The school is located only a few hundred meters from Garissa University, where 147 people were killed by Al-Shabaab terrorists in early April. Hide Caption 1 of 8 Photos: Kenyan schools live in fear of Al-Shabaab James Ndonye, the headmaster of the school, says five out of 11 teachers have left in the past year amid rising fears of an attack by Al-Shabaab on the school. He has replaced them, but it has not been easy. Hide Caption 2 of 8 Photos: Kenyan schools live in fear of Al-Shabaab Al-Shabaab have launched a series of deadly attacks over the last few years in the region mostly targeting Christians. Many of the math and science teachers in this area are Christian. There is only one security guard for Ibnu-Siina school, and he is unarmed. Hide Caption 3 of 8 Photos: Kenyan schools live in fear of Al-Shabaab The school teaches mathematics, science and English. But it's an education that Al-Shabaab is trying to prevent the children from obtaining, according to Ndonye.﻿ Hide Caption 4 of 8 Photos: Kenyan schools live in fear of Al-Shabaab Lessons and metrics are graphically illustrated on some of the school walls.﻿ Hide Caption 5 of 8 Photos: Kenyan schools live in fear of Al-Shabaab Kenya's students -- like the girl picture here -- aren't the only ones under threat. In Nigeria around 270 girls were kidnapped from their school in Chibok by Boko Haram last year. Hide Caption 6 of 8 Photos: Kenyan schools live in fear of Al-Shabaab A class timetable for the school in Garissa. ﻿ Hide Caption 7 of 8 Photos: Kenyan schools live in fear of Al-Shabaab A sign outside the Ibnu-Siina school provides some small light relief to students who live in constant fear of an attack. Hide Caption 8 of 8

During her two years in north eastern Kenya she has worked in some of the most dangerous areas such as Mandera and Wajir -- places that have suffered numerous attacks on Christians.

She is determined in her faith. "If you can go to your place of work you can also go to a place of worship," he said.

The diocese has received words of encouragement from the Pope himself. At the invitation of the diocese, Bishop Alessandro tells us that the Pope added Kenya to his Africa trip in November. He says members of the congregation will be chosen to travel to Nairobi to meet him.

For now though, he and his bishops are focusing on the daily task of keeping their flock safe as best they can. The bishop tells us: "We are people of God, we are people of faith. God never abandons us and maybe in moments when we feel that we are left on our own. There are those moments that God might be very close to us. Even if we don't feel him."