KABUL, Afghanistan — Violence escalated Monday here in the Afghan capital during a second day of protests by minority ethnic Hazaras over the arrest of an anti-Taliban militia leader. Officials called him an abusive rogue, but supporters said he was a hero who had defended Hazaras from insurgent attacks.

Health officials said at least 19 people were wounded. There were unconfirmed media reports that four others were killed when police confronted hundreds of angry demonstrators, firing into the air and barricading routes out of the Hazara-dominated west Kabul area.

Officials at the Interior Ministry said 48 police officers were injured and eight police checkpoints set on fire during two days of demonstrations. They said no one was killed. An aide to President Ashraf Ghani tweeted that the protesters were committing "vandalism and armed disobedience."

Monday's street clashes, which came as Ghani departed for a conference in Geneva on Afghanistan's future, marked a rapid escalation of unrest among Hazaras, who are also Shiite Muslims. Members of a once-repressed minority, they have strongly supported Afghan democracy but have faced relentless attacks by Islamic State terrorists and periodic Taliban abuses. They assert that the government has done far too little to protect them.

One evening last week, thousands of Hazaras marched to the presidential palace, demanding that the government send more troops to defend villages under Taliban siege in central Ghazni province. Extra government troops were sent, but fighting raged for days while thousands of villagers fled to other regions.

This time, the source of the protesters' anger was the detention Sunday of Abdul Ghani Alipur, the leader of a private Hazara militia who is known as "Commander Sword." He and his forces have often patrolled a highway through Taliban-infested regions, gaining heroic status among Hazaras.

"Alipur changed the valley of death into a safe way for Hazara passengers," said Amiri Yagana, 29, a government worker who participated in the protests. "He is a fundamental pillar of government in Hazara areas. He has only fought the Taliban. Why should he be arrested?"

Hussain Ali Baligh, a Hazara member of the Wardak provincial council, said Alipur has "supported the people and the government" by protecting the highway through Wardak. Hazaras have been beheaded, kidnapped and robbed in the province, but government forces have done little.

Government officials portrayed Alipur in a different light, saying he had established an "illegal armed group" and conducted "criminal activities" in the guise of fighting the insurgents.

In a statement Monday confirming his arrest, the National Directorate of Security said Alipur had employed 150 men and weapons to extort traders, harass people and take police hostage. "Under various pretexts," it said, he had engaged in illegal activities and would be "dealt with in a serious manner."

There were also contradictory signs of Alipur's reputation in provinces where he was active. Demonstrations demanding his release were reportedly held Monday in Hazara areas of Wardak, Daikundi and Bamian provinces, but in Wardak a separate group reportedly gathered to demand that he be put on trial for alleged abuses.

The conflicting opinions of Alipur reflected the complicated allegiances among Pashtun and Hazara groups in the belt of provinces stretching from Ghazni in the south up to Bamian some 200 miles north. Taliban insurgents enjoy some support in Pashtun areas; they have harassed some Hazara communities and left others alone.

There have been reports of local and regional deals between Hazara and Taliban leaders that recently collapsed, as well as reports of Iranian influence in the escalating violence. Iran has long-standing ties with Afghan Shiites, but it has also been accused of backing the Taliban.

Despite Alipur's arrest as a brigand, he was widely praised on social media. Eid Mohammad Joya, a finance manager, wrote on Facebook that he deserved a medal, not imprisonment.

"Government made a big mistake to arrest the commander, and it will pay a heavy price if he is not released," he wrote.

The Post's Sayed Salahuddin contributed to this report.