NAIROBI, Kenya (AP) — Protesters carried coffins and red crosses to downtown Nairobi on Tuesday, a vivid memorial for the hundreds of Kenyans killed in recent terror attacks, as pressure builds on the government to halt a steady onslaught of gunfire and grenade assaults.

In Kenya's north — where 28 people riding a bus were killed by Somali gunmen over the weekend — non-Muslim Kenyans sought refuge at an army post on Tuesday, fearful of another attack by fighters of Somalia's Islamic extremist group, al-Shabab. On Saturday al-Shabab attackers hijacked a bus near the city of Mandera, singled out non-Muslims and shot them in the head, the latest terror attack in this East African nation.

Twenty-two of the 28 people killed over the weekend were teachers leaving Mandera for their holiday break.

Earlier this year gunmen near the coastal resort town of Lamu killed around 50 people. In 2013 al-Shabab terrorists attacked a Nairobi mall and killed 67 shoppers.

"One thing we want to do is put it clear to our leaders that the state of security is worrying for all Kenyans. We need to put our security organs in place," said Achieng Otieno, a 35-year-old IT consultant who attended Tuesday's demonstration. "How do you explain someone coming from nowhere and shooting 28 people?"

Militants allied with al-Shabab have carried out more than 100 bombings and gunfire attacks inside the country since Kenya sent military troops into Somalia in 2011. In response Kenyan authorities have shut down mosques, carried out mass arrests of Muslims and, according to rights activists, have sometimes killed Muslim leaders, acts that critics worry serve to perpetuate the cycle of violence.

Allegations that police manning the border checkpoints with Somalia allowed the Mandera attackers through must be investigated, said one of the country's largest papers, the Daily Nation, in an editorial Monday. The paper questioned the police force's commitment to fighting terrorism.

"Dear Mr. President, what are you doing as Kenya burns?" another opinion column on Tuesday was titled. "The Mandera bus massacre is the last straw. After every terrorist and bandit atrocity, we hear the same defiant words copied and pasted from one speech to the next. They are beginning to sound like a stuck record."

Near Mandera, dozens of non-Muslim residents camped out at an army checkpoint in hopes the soldiers will protect them.

Mandera's non-Muslims say they want the government to evacuate them. The region's governor, Ali Roba, told those scared residents Tuesday that evacuation is a sign of fear and defeat — a terrorist victory. After the attack, Roba demanded a complete security overhaul. Jackson Kasauni, an army officer, told the residents that the military would increase patrols.

"We don't want to give our sovereign country to other people, but we have to sit together, united, despite being of different religious backgrounds," Kasauni said.

Kenyan Deputy President William Ruto said on Sunday that Kenyan security forces killed more than 100 al-Shabab fighters after the bus attack. The claim has been met with wide skepticism by many Kenyans.

At the Nairobi demonstration, a small group of protesters discussed security efforts against Islamic extremists. Security forces last week closed down four mosques in Mombasa. Al-Shabab said the bus attack was in retaliation for that move.

"I think the government has played into their hands by closing the mosques and the extra-judicial killings," said Newton Kidali, a 30-year-old accountant. "I think if those Muslim clerics are committing crimes they should just be arrested."