NEW DELHI — A special plane carrying the bodies of 38 Indian construction workers killed by the Islamic State group in Iraq arrived in the northern Indian city of Amritsar on Monday.

Indian Junior Defense Minister V.K. Singh flew back with the bodies.

The Islamic State group abducted and killed the workers shortly after seizing the northern Iraqi city of Mosul in the summer of 2014. Iraqi authorities discovered the remains in a mass grave last year after retaking Mosul, and identified the bodies last month.

Forty workers were initially abducted. One escaped and the presumed remains of another have yet to be positively identified. Authorities are awaiting DNA samples from a close relative.

The workers were mostly from northern India’s Punjab state and had been employed by a construction company operating near Mosul. Around 10,000 Indians lived and worked in Iraq at the time. The victims may have been killed because of their Hindu or Sikh faith.

The Islamic State group swept across northern and central Iraq in 2014, eventually seizing a third of the country. Iraqi forces backed by a U.S.-led coalition eventually drove the militants from all the territory under their control in a grueling three-year campaign. The militants are still carrying out insurgent-style attacks.

Dozens of mass graves have been found in areas held by the extremist group, which boasted about massacring its enemies and posted videos and photos of many of the mass killings online. Iraq has only managed to excavate a few of the sites due to a lack of funding and specialized staff.

“We are thankful to the authorities in Iraq for the help to locate the victims and exhume the mortal remains. The government of India did its best to know about the missing Indians,” Singh told reporters in Amritsar.