A social media campaign to raise funds for the family of a Muslim teacher who died protecting Christians during an attack in Kenya is gaining traction, with people hailing him as a "genuine hero" and a symbol of the country.

Salah Farah was shot after refusing to be separated from Christian passengers during an al-Shabab attack on a bus travelling from Mandera to Nairobi last month.

He succumbed to his wounds on Sunday, leaving behind four young children aged between two and 10, and a pregnant wife who is expected to give birth as soon as next week.

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After his death, an online campaign was started to raise funds for the teacher's family.

"Salah is a hero," Abdullahi Derow, the 26-year-old activist who started the #HeroSalah Twitter campaign, told Al Jazeera.

"He was the only male child in his family, his father is now very old and his kids are very small," Nairobi-based Derow, who is also from Mandera, said.

Let's support the family of hero Salah who has since succumbed to the bullets in the Mandera bus attack #HeroSalah pic.twitter.com/wuJaTL7cbb — Abdullahi Derow (@AbdullahiDerow) January 21, 2016

"I tried to think about how we can do this for the family, as Kenyans, at least to appreciate what he has done not only for Kenyans but for humanity," explained Derow, who got the approval of Farah's cousin Rashid, and now guardian to his children, before launching the campaign.

Rashid confirmed to Al Jazeera that the family had given the go-ahead.

"The children need a shelter, they need education, they need to be cared [for]," Rashid told Al Jazeera. "The father and mother are the same."

He added: "Salah was well-respected, a religious man, who had just been promoted to deputy headmaster of a big primary school - he was having a lot of respect in the village".

So far, the campaign has raised over 150,000 Kenyan shillings ($1,460) mainly through the M-Pesa money transfer service, with donations ranging from $200 - sent by a female university professor in Canada - to just a few shillings.

"Even if someone sends just a few shillings, it can make a big difference," Derow said.

Despite being pushed out of Somalia's major cities and towns, al-Shabab continues to launch deadly attacks across the Horn of Africa country.

The group, which last week assaulted a military base run by Kenyan troops as part of an African Union force in the Somali town of El-Ade, has also carried out many attacks inside Kenya.

Derow said the outpouring of support for the campaign was sending a "clear message" to al-Shabab that Kenyans were united.

"There is a feeling of patriotism. Kenyans are feeling by helping the family of #HeroSalah and educating his children is a defiance to al-Shabab," he said.

"We are one in honouring are heroes."

Your rewards are in heaven brother.what you did is legendary. #HeroSalah — owitichris (@owitichris) January 23, 2016

#HeroSalah you paid the ultimate price, you are a hero — HEMEDI THFC® (@ABU_HEMEDI) January 23, 2016

Salah Farah told alShabab "kill all of us or leave us alone" He's gone, His kids need U #HeroSalah #KULUNFoundation pic.twitter.com/fayoW1aFzk — Carol Radull (@CarolRadull) January 22, 2016

#HeroSalah you courageous spirit will always live on in us. — Duncan Ondimu (@matundura78) January 23, 2016

#HeroSalah Your contribution to humanity was Awesome! Take this heart commendation, go in peace, as we live to follow your light. — hezbee (@hezb7) January 23, 2016

Thank you #HeroSalah for sharing the same ideas with other Kenya's.you stood by us when everyone remained silent. — owen (@AlfreMakau) January 23, 2016