Mourning relatives of 29 people murdered by a disgruntled soldier in Thailand held Buddhist prayer ceremonies Monday, as questions are still left unanswered  over how and why the shooting spree happened.

Authorities said the attack was carried out by a single gunman — a disgruntled soldier who opened fire on strangers before he was fatally shot Sunday at a shopping mall. Another 58 people were wounded.

The killer, armed with automatic weapons, held out for 17 hours as hundreds of shoppers cowered in toilets, storerooms and under tables.

As Korat — and the country — mourned, there were growing questions about why the gunman went on a killing spree over an apparent private debt to a senior officer and how he was able to steal weapons, including an M60 machine gun, and hundreds of rounds of ammunition.

The attacker was identified as Sgt. Maj. Jakrapanth Thomma.

The death toll surpassed Thailand’s last major attack on civilians, a 2015 bombing at Bangkok’s Erawan Shrine that was allegedly carried out by human traffickers who killed 20.