At least 10 people were killed on Wednesday in a blast at a technical college in Crimean port city of Kerch, Reuters reported. At least 50 others are believed to be injured. Russia annexed Crimea from Ukraine in 2014, prompting Western sanctions.

An explosive device rigged with metal fragments went off in the canteen of the college, Russian Investigative Committee’s spokesperson Svetlana Petrenko said, AP reported. Most of the victims were students, she added.

Kremlin said it was investigating whether it was a terror attack. Kremlin spokesperson Dmitry Peskov said President Vladimir Putin had ordered security services to conduct a thorough probe.