The slaughter continues.

CAIRO — An off-duty policeman boarded a train and opened fire on Tuesday, killing a 71-year-old Christian man and wounding his wife and four others, the Interior Ministry said. The attack, less than two weeks after the suicide bombing of a church killed 21, sparked new demonstrations by enraged Christians who pelted police with stones in southern Egypt.

The church attack on worshippers leaving a New Year’s Mass in the Mediterranean port of Alexandria touched off three days of riots and demonstrations by furious Christians who criticized the government for failing to protect them and vented over what they see as persistent discrimination.

All of the casualties in the latest attack were Christians — four of them women — raising concerns it will ignite a new wave of protests by a community still traumatized by the suicide bombing.

Soon after the attack, hundreds of angry Copts gathered outside the hospital where the wounded were being treated in the central Egyptian province of Minya and stoned police.

It was not immediately clear whether the gunman knew his targets were Christians. But four of the five wounded were Christian women who stand out in the conservative south as they would probably not have been wearing headscarves as most Muslim women do.

The ministry statement identified the policeman as Amer Ashour Abdel-Zaher, a 23-year-old Muslim, and said he boarded the Cairo-bound train at the town of Samalout in Minya province and opened fire on the passengers with a handgun.