Two people were arrested and one appeared before a French judge Monday as part of a terrorism-related investigation of the shooting attack that killed five people last week near a Christmas market in Strasbourg, the Paris prosecutor's office said.

An official close to the investigation said the man who was in court is suspected of involvement in supplying the weapon that alleged gunman Cherif Chekatt used in the Dec. 11 attack. Chekatt, 29, died in a shootout with police in Strasbourg Thursday.

The two detained Monday also were suspected of "playing a role in supplying the firearm," said the official, who could not be named with the case ongoing. Their arrests bring the number of suspects in custody since the attack to three; Chekatt's parents and two of his brothers were questioned by police last week and released.

The death toll from the attack increased to five Sunday night after a Polish man died of his wounds in a Strasbourg hospital. Barto Orent-Niedzielski, 36, lived in the city, where he worked at the European Parliament and as a journalist. The other casualties include a tourist from Thailand and an Italian journalist covering the European Parliament.

According to some reports, Orent-Niedzielski fought the shooter and stopped him from entering a crowded club, possibly preventing more deaths.

Polish President Andrzej Duda wrote early Monday on Twitter that "I knew him by sight. I am shocked. I had not realized that he was the one mortally wounded protecting other people. Honor to his memory. RIP."


Samuel Petrequin in Paris and Monika Scislowska in Warsaw contributed to this report.