MOSCOW (AP) — Flags are flying at half-staff across Russia as the country mourns the victims, many of them children, of a shopping mall fire in Siberia.

Russia is observing a day of mourning on Wednesday, with thousands of people across the country bringing flowers and stuffed toys to makeshift memorials.

Officials say 64 people died on Sunday in the fire at the mall in the city of Kemerovo, which was packed with parents and children the first weekend of the school recess.

Investigators identified a short circuit as a possible cause and said the emergency exits were locked shut, hampering an evacuation. Some of the victims died in a locked movie theater.