BANGKOK (Reuters) – Thai Prime Minister Prayuth Chan-ocha on Monday ordered law enforcement agencies to tighten gun ownership rules and crack down on drug use following a mass killing by an ex-policeman at a daycare centre that left has the nation in shock. A total of 36 people including 24 children were killed in a knife and gun rampage last week by an ex-cop who later killed himself in Uthai Sawan, a town 500 km (310 miles) northeast of Bangkok. It was one of the worst child death tolls in a massacre by a single killer in recent history. Prayuth has instructed authorities to proactively sear…