KABUL — Hundreds of protesters rallied for a third day Sunday near the site of a deadly bomb blast in Kabul, demanding greater security and the ousting of the US-backed government of President Ashraf Ghani.

Protesters staged a sit-in under tents in the blazing heat — while fasting for the Muslim holy month of Ramadan. They clapped and chanted ‘‘God is great’’ a few hundred yards from the crater where a massive truck bomb killed nearly 100 Wednesday.

About 500 antigovernment protesters also rallied for change in the western city of Herat.

The protests were peaceful, but the country remains tense after antigovernment protests Friday and a gruesome triple suicide bombing that killed 20 Saturday at a funeral for a protester according to the public health ministry.

Protesters said they were angry the government could not keep the country safe, and demanded the arrest of security officials who allegedly fired into the crowd Friday, killing six.

‘‘The duty of the government is maintaining of security. No one can prevent protests,’’ said Jawed Kohistani, a retired general and military analyst who spoke at the demonstration.

“Why were they not able to prevent the attacks with all the money and resources they have accumulated from the world? This shows their failure,’’ Kohistani said.

An intelligence official for the National Directorate of Security said Sunday that agents had arrested a panicked, barefoot man who fled from the funeral bombing. They believe he may have been a fourth suicide bomber.

The man left high-top sneakers fitted with explosive devices at the scene, the official said.

The embattled Ghani, in a video statement released Saturday evening, blamed ‘‘savage terrorists’’ trying to ‘‘break down the nation’s spirit’’ for the violence.

‘‘They want to create confusion, division, lack of confidence, and a vacuum in the nation and the government,’’ the president said. He promised reforms in military and civilian sectors of the government and vowed to prosecute the ‘‘culprits’’ who fired on protesters.

Security experts say that if the protests catch hold and widen it could weaken Ghani’s fragile coalition government, already worn thin by the Taliban insurgency and militants linked to the Islamic State.

On Sunday, the demonstrators — most of them from Afghanistan’s Tajik ethnic group — hunkered down under two tents on an avenue leading to the presidential palace Sunday in Kabul’s diplomatic zone.

Some had spent two nights there already, breaking their daily fast with the traditional iftar meal at the site.

They accused Ghani’s government of killing the protesters and of orchestrating the suicide attacks to ‘‘wipe out’’ and ‘‘subdue’’ the Tajiks, the second largest ethnic group after the Pashtuns, Afghanistan’s traditional rulers.

Ghani, like most of the Taliban insurgents, is a Pashtun.

‘‘They are bullying us, tearing us apart so that they can rule on us. This movement will become nationwide. Our blood from drops will become a river and will turn into a flood and will submerge our enemies,’’ said Kabul University professor Faizullah Jalal, who spoke at the demonstration.

Organizers hope to expand the protest beyond the Tajik ethnic group to attract those from Uzbek and Hazara minorities as well.

One of the protesters, Rahim Frotan, 26, said he had spent three days and two nights at the protest because ‘‘we don’t want any more suicide attacks in Kabul.’’ He said Ghani’s security team should be fired — ‘‘they have all failed us.’’

The protesters had their own security. Abdul Hameed Khorasani, showing an assault rifle and several magazine bullets, said he expected more protesters will join the crowd Monday.

Khorasani said the organizers will present their demands in writing to the government but will not back away from their key demand — the end of Ghani’s government

Ahmad Zubair Masood, one of the protesters, used the term ‘‘Afghan Spring’’ Saturday to describe the demonstrations in Kabul.

‘‘This is not Cairo, this is Kabul,’’ he said. ‘‘People are arriving from all provinces. Tanks and bullets won’t stop them.’’

While accusing security personnel for using ‘‘excessive’’ force during Friday’s protest, some members of the civil society said the rally was hijacked by a group of armed men.

The United Nations special representative to Afghanistan, Tadamichi Yamamoto, has warned that the protests could lead to further violence and strongly urged opportunists not to use the emotional moment to cause instability.

The recent spate of violence comes as President Trump is reviewing the United States’ Afghan policy amid a push by some members of his administration to send more troops to Afghanistan to fight the Taliban and other militant groups. About 8,000 US troops are currently deployed in Afghanistan.

In a separate development Sunday, Afghan officials said at least six police officers were killed after two fellow police opened fire on them in southern Kandahar province.

Two provincial officials confirmed the attack, which they said also wounded the Kandahar City district police chief. Both spoke anonymously because they were not authorized to brief the media.

Qari Yusouf Ahmadi, a Taliban spokesman, claimed responsibility for the attack in a statement saying that both attackers were their men who joined the police ranks just to carry out such an attack and both devoted their lives for their aim.

Taliban insurgents have increased their attacks against Afghan security forces across the country.